I've managed to avoid this thread so far, largely because I'll probably be accused of White Knighting less than perfect women. However I can hold my silence no more.
Many of us more mature punters actually like older WGs, so purely on an age and lived a life basis, stretch marks are an occupational hazard. I have yet to come across a girl with stretch marks so bad that they were off putting. One of my favourite girls has a bit of a saggy tummy with stretch marks, but is otherwise super hot.
Excessive tattoos can also be a turn off but the odd, cute discrete ones can be nice. Regarding other marks such as scars, again it's difficult to generalise as you can't know how you might react if, for instance, a WG exposed some horrendous burn scars or similar. That said, my regular, who is extremely petite and otherwise flawless, has a childhood scolding scar right below her gorgeous tiny boobs. Rather than turning me off, I find it really cute, especially as she is completely comfortable with it.