I don't have any pre-owned RMs but have bought plenty of other brands second-hand: mainly Pradas but some Ferragamos & others. I just don't have the money, to buy bags at their retail prices, simple as that.
I like real vintage Dior, so I have to get them pre-owned.As far as leather bags go I like bright colors and plain shapes, and until I discovered RM, most affordable bags like this were old Pradas.
Prada for a while did the same few simple leather bag styles again and again but in many unusual colors including blues and greens, at one time they even had periwinkle and dark periwinkle. There were a couple of great years when everyone got rid of these and eBay was full of them.
Overall I've had mostly all positive pre-owned bag buying experiences. My worst was a bag that had not only a stained lining, but was still full of rubbish from the previous owner. It was a leather Lambertson Truex and only about $20, but still... the rest of my pre-owned bags have been fine. I just got a Prada from a few seasons ago that looks untouched, and cost about 1/7 of its new price.
- ask questions and ask for pictures, particularly about lining, handles and corners
- when a seller says, this is a small mark but really 'not very noticeable', ask even more questions
- beware of pre-owned white or cream bags, there's no such thing as 'a little bit used' - if they're grubby, they're grubby
RM is great! There's such a fast turnover of colors that even the new bags go on sale at the end of each season, and most of the styles look better 'worn in' anyway.