I buy and sell on eBay and find it to be generally well worthwhile. I have only been disappointed a few times when items have been used when advertised as new without tags. In almost all cases sellers have been particularly helpful if they were at fault and and in the one case where the seller was a bit dodgy I had the item refunded but not the postage. That was my fault anyway from buying from her... I should have guessed she was not the most wonderful seller by the feedback she left for other people (very very nasty!!).
My few selling experiences to date have really surprised me. A beautiful, current-fashion, brand name shirt sold with only one bid at a low price... and the bidder never paid! And other second hand items have sold for far more than I expected. Just goes to show that what you
think people want is not necessarily what they want at all. Kind of makes it fun, I think!
As for security issues, I have no qualms about giving people my bank account details. It speeds up the process and has caused me no hassles to date. Perhaps there are risks here but I can't think of any, and further to that, doubt that eBay would allow it if there were significant risks in so many people providing their banking details. Hey, if my credit card details can be nabbed by an employee of a major un-named tollway operator
then what can happen with a few details on eBay that relate to an account with not that much cash in it anyway??
My understanding of why people don't want zero-feedback bidders bidding on their auctions is that sellers don't like them because they have unrealistic expectations, leave negative feedback without contacting the seller first to resolve issues, don't pay, don't understand 'the rules', or that they might be trying to auction bomb the particular listing (bidding with no intention to pay, usually across many of a seller's auctions). Personally, I think everyone has to start somewhere, and newbies often place high bids, so I have no issues with them.
Interested to read about all of your experiences... there are many bargains to be found!