It REALLY depends. I've buy silicone dildos off there easily because I could boil away the ownership. For silicone vibrators, it depends. Metal, glass, silicone, etc, I would have no problem with because of the fact that I could easily clean them and get away any love juices...but the reputation of the seller would have to be amazing. I'm also not going to pay anything close to full price for something they got to enjoy too.
Things like jelly toys? No. Anything that is below a 7 on the safety thing means it's super porous and keeps stuff on it easily and I can't do any amount of cleaning to get it all off.