I played fretless instruments for so long I don't even notice, had to think about it for a sec, I have two guitars without any. Classical and ironically and Epiphone DOT. It may have some on the side, i forget, not handy.
I definitely would use the correction fluid or put quality ones on from LMII or wherever.
I have an ancient classical that someone took a knife too, i think. I didn't think it was intentional at first, but there there is a big old cut at the 7th fret....the more I thought about it, it is clearly multiple cuts, with ink or blood or whatever rubbed into it..I think it was intentional.
But he's pretty funky all around