I've never come across scams with fabric on ebay, but it's a real game of hit or miss, with the misses beating out the hits by a wide margin. I've probably bought five lengths off ebay. One came with with snags and was unusable. Buyer refunded and told me to keep it. Another time, the seller sent me the wrong stuff, which I had to return. Never got what I ordered. I've bought fabric that looked completely different from the picture and had to resell, and I've bought a length that looked great, but felt awful. I just threw it away. 0-4.
Then, I bought a suit length of Lumb's Golden Bale in the exact type of cloth I wanted for 1/5 of the price that my tailor would charge. That was nice, but not a particularly good success rate. I gave up shopping for fabric on ebay. It's not worth it.