I used to love Ebay but its losing its lustre. Ebay does do a reasonable job of ensuring you are happy with your purchase. If you have an issue with a seller Ebay's dispute resolution system mostly ensures good lines of communication between you and the seller and Ebays team.
That said making the buyer return goods that simply don't match what was offered and at their expense is not on.If the seller wants their questionable items back it should be on them to meet the cost. Assuming of course the buyer can prove his/her case and this is not normally not that hard.
I have found in the last six or so months there is an ever increasing presence of shifty sellers on line. Especially from Hong Kong/China. So much so I'm for the most part no longer willing to buy goods from this region. By contrast UK/US sellers seem to be for the most part honest and I have rarely had reason to doubt them.
In summary Ebay is, in my opinion, a step up from sites like Alibaba but it needs to do more to police its sellers and come down harder on those who don't do the right thing by the customer.