In my last choir rehearsal, while going over a new piece, after I said, "Let's go back to the beginning and go over the 'oo's", my lead tenor, whom I respect immensely as a musician, responded "Uh, shouldn't that be the 'oh's? If there's an 'h' it's pronounced 'oh'."
So, I looked at the music and saw "Ooh". Now, to me, two "o"s means "oo", regardless of the "h". This started a short but lively discussion which I stopped before it went on too long... We rehearsed it as "oo".
I hate seeing "lololol", because in my head I hear "Laughing out loud out loud out loud". I get that others read that as "laughing out loud for a really long time", or maybe "ha ha ha ha ha", but not me. It drives me nuts. Letters should not be repeated to indicate that the word should be spoken slowly. Certainly not in music! We have notation standards for that. A drawn out "Oh" would be notated as "Oh---".
But, this is all just my opinion. I have no authoritative source to back it up. Can anyone provide a definitive answer one way or another and back it up with evidence?