I've bought a lot of fabric from ebay, but usually named fabric, Moda, Kaffe Fassett and Liberty mostly. Twice I bought unamed charm squares because they were in a colour I needed but some of them were so thin you could see right through them and I ended up using them in a scrappy quilt.
As most people on here have said, read the sellers feedback (I only buy from sellers with 100% feedback) and also the item description carefully before buying.