Maybe it just stands out for me better when its italicized. I can't say I'm troubled by it one way or the other.
I'm a comma whore. I use them like they're going out of style. It is a habit I'm trying to break. I mention this because I am the last person who should be giving any sort of advice on grammar. But I feel the need to mention that I've noticed people bringing up names like Hemingway and Stephen King in justification for using italics for internal thoughts. How is this helping the OP? With all due respect to the OP, they are not Stephen King or Hemingway. King is filthy, stinking rich as far as writers go (even more so) and he can probably just about do whatever he damn well pleases when writing a book and his editor isn't going to make a lot of noise over it. Stephen King also started out understanding the rules of grammar before he broke them which I believe he said as much in his book On Writing: A Memoir of the Craft. Now I don't know squat about writing a manuscript but I have seen manuscripts as they are written out and as I picture one in my mind, I can only imagine the absolute eyesore it must be trying to spot every piece of italicized text. On the other hand, underline text would stick out like a sore thumb and thus much easier to spot. Agents and editors have to do enough reading as it is. They're not going to be interested in straining their eyes any further. My advice: follow the rules. If you ever become the next Hemingway or Stephen King then by all means, break them to your heart's content but until then, you're better off learning and abiding by the current rules and standards of the craft. Remember, there are countless people out there who do follow these rules and who still don't get noticed. I don't think your over-italicized manuscript is going to elicit any oohs and ahhs from the publishing world. I'm hardly an authority but I would say that creative storytelling and characters trumps creative formatting any day.
I agree that there are things more important than "creative formatting", but I don't agree with the underlining part. Are you suggesting that authors underline parts they eventually want italicized? Or are you saying that finished books should have thoughts underlined? Either way, I don't agree. As far as I know, underlining something in an MS or a finished novel would be much closer to "creative formatting" than italics would be.
It shall begin: You look into a mirror and seee your hair as black as a raven and your eyes more emeraldy than an emerald.
[cont.] Then your eyes snap open from the nightmare you had been having previously until this moment. You walk over to a mirror and examine your reflection, only for real this time because you were dreaming previously before this time looking into a mirror.
The wayward curl of hair you see in your reflection, snaking its way across your forehead, makes two brain ganglia connect and create a bridge through your hypothalamus into deep memory. The ozone smell of a flashback fills your nostrils and you begin to info-dump backstory...
So Chosen was this womb that it was gifted with the power of 4th Wall Breaks, as just happened right now. The mirror before you goes all meta and fuzzy. Where were you? Oh, yes... The womb... You were born in a womb, but not just any womb. It was a Chosen Womb....
The womb, nearly your tomb, a subcategory of doom flume, does not have enough... room. Though to groom was its purpose, somethings just not right. Between you and this Chosen Doom Flume Womb, you're preparing to fight. (real talk though, this isn't easy.) eta: also, I added terrible odd and offbeat rhyming. Hope everyone's cool with that.
Actually, since the OP was referring specifically to a manuscript, that is what I was talking about as well. The way a manuscript is formatted can make picking out italicized text very tedious and would likely turn off an editor or potential publisher. So if the norm is to use underlined text instead because it is easier to spot then it seems clear that, that is what one should do.
I can't see any mention of a manuscript in the OP. And I agree that the norm was underlining back when people were submitting paper manuscripts that had to be retyped, but just about everyone is using digital these days, so I think that rule is outdated.
My mistake. I see now that she didn't. The discussion shortly after the first post seemed to have evolved in referring to manuscripts and I must've convinced myself that it started with the OP. Anyways, my post was certainly referring specifically to manuscripts since I was under said false assumption when I wrote it. Italics weren't even possible on a typewriter and it seems convoluted to try to use them when writing by hand so since I was referring specifically to the ease at which to spot underlined text over italics, I fail to see how the digital age would make such a rule obsolete. If italics are too difficult to find within a mass of text, it would only make sense that an editor would prefer it to be underlined for mere ease of access.
From everything I've read, @BayView is correct. All of the manuscript submission guidelines I've seen that have been written in the last several years indicate that, while publishers used to prefer underlining text that should be italicized in print, now they simply want it italicized from the outset.
I think you may be overestimating how difficult it is to see italics. I mean, finished books have italics, right? So... if readers can see them in books, why wouldn't editors be able to see them in manuscripts? I've had lots of manuscripts (with italics) accepted by various publishers. I've never heard a hint of anyone wanting them to be underlined. If an agent/editor specifically requests underlining instead of italics, I think it would make sense to go along with that request. But just default MS format? Do you have a current source saying to underline passages that will eventually be italicized?
WHAT ABOUT THE WAY YOUR GIGANTIC BREASTS WITH THEIR ETERNALLY PERKY NIPPLES STOOD PROUDLY OUT ABOVE YOUR FLAT STOMACH AND TONED, SILKY THIGHS, DAMNIT?
You admire your eternally perky nipples, as pink as those flowers called pinks, that stand proudly out above your flat stomach and toned, silky thighs, like proud nipples. Then you wake up. It was all a dream! You walk over to the mirror and use your eyes to look at your reflection but for real this time because the last time was a dream within a nightmare and you weren't really looking with your eyes but only with dream eyes which are different and less eye-y.
NIGHTMARE TITTY DREAM YOU HAD WHILE INSIDE THE CHOSEN WOMB, PRACTICING YOUR MAGIC BECAUSE UR A WITCH BUT MAMMA DON'T KNOW SHIT.
SO UR MAKING OUT WIT UR GIRL RIGHT N THE PHONE RINGS N U ANSWER AND IT SAYS "WUT R U DOING WITH MY DAUGHTER" AND YOU HANG UP AND UR GIRL SAYS "BUT MY DAD IS DEAD" So who was phone? (Also I think our masterpiece, TITTY DREAM, deserves its own thread.)
I do not because as I already mentioned, I don't actually know anything about writing a manuscript. I wasn't making claims, only speculation concerning following the rules (whatever they may be) from conversation earlier in the thread. For me personally, I find italics difficult to focus on but that's just because I have shit eyes. To be fair, I'm willing to bet that editors do a lot more reading than does your average reader. They also have to re-read things a lot more and they're not really reading for pleasure. They have to keep a critical eye open. I imagine that italics would be more difficult to note than underlined text in a manuscript because of the spacing and how easy it would be to gloss over text that has a slight slant as opposed to something that is underlined. <--- I mean, that's a lame example since despite my rambling, it's still not quite as long as a manuscript. So if the norm is to underline quotes or book titles or what have you as opposed to italicizing them, all I'm saying is that I think it would be best for a new writer to follow that rule until such a time that they become comfortable with their editor or publisher to start using their own stylized formatting flair. Personally, I've always been one to use italics for internal dialogue because I like to keep a clear distance between my narrator and whatever character is on scene.