I had an interesting 'conversation' with ebay earlier this month on this topic. I've edited out most of the waffle, but basically it went like this:
"I understand that ebay will be able to pay money into my bank account, but will ebay be able to WITHDRAW money from my bank account? If so, for what reasons, and what protection will I have?
To answer your question, yes eBay can withdraw from your bank as well, however this is generally a pretty rare situation.
It would happen when your available balance drops into the negative amounts. If you sell a lot, this almost never happens as your new sales will generally cancel out things like returns which could make the amount go negative.
I do more selling than buying and expect to continue using Paypal. Can transactions made through Paypal affect whether Ebay takes money from my bank account?
Paypal is no longer the payment processor so all of the money paid to you as a seller would affect your bank (usually paying into)
In other words, it doesn't matter how a buyer pays, we process the money the same way
Thank you for being the best part of eBay and I hope you have a wonderful rest of your day"
So they can take money out of your account as well as pay it in, and there was no word of any protection, unlike direct debits where there is a Direct Debit Guarantee published. I haven't found time to follow this up, but I am very dubious about signing up to it.
They also insist that it has to be a bank account, not a savings or credit card account.
George B.