Is this an auction or a local listing where you'd have an opportunity to inspect the rims?
I'm assuming there's something special about them that has you interested but I wouldn't buy them unless I could see them. At least the seller appears to be honest and that's a good sign.
There's not very much to go on from what you've posted but depending on the rim and the location of the dents, it's possible that if these are hooked rims and the "hook" has been affected, it may not hold a tire as well.
I suppose it's also possible that the rim has been weakened. What's a small dent now may the starting point for a big nasty crease later.
Of course, I know next to nothing about rims, so keep that in mind ;-) No one else seemed to be responding.
Anyway, if this is an Ebay auction, I'd pass.