From the Paypal help screens:
Sellers who offer a PayPal payment option on eBay, and then reject a credit card payment, or other payment types (such as a bank transfer) run the risk of being reported to eBay as a Non-Selling Seller, after which one or more of the following actions may be taken:
Listing cancellation
Forfeiture of eBay fees on canceled listings
Limits on account privileges
Loss of PowerSeller status
Account suspension
If you sell on eBay using a PayPal Personal account, you can accept PayPal account balances and bank account payments with no additional fees. However, if you receive a credit card payment from an eBay buyer, you need to upgrade to a Premier or Business account.
PayPal Premier and Business account holders are charged a small fee to receive payments. The fee is based on the monthly payment volume. For details, see the fees page.
Additionally, sellers can not communicate to eBay buyers (for example, in an item description) that they only accept, or will not accept, certain forms of PayPal payments.
Violation of this policy can result in the cancellation of the auction. The consequences of refusing to accept a certain type of PayPal payment after an auction ends is stipulated in eBay's Seller Non-Performance located at
http://pages.ebay.com/help/policies/seller-non-performance.html.
Buyers can also report a seller through this link by selecting 'Report the Seller' in the additional Information section.
Violations of this policy include language such as:
"I do not accept credit card payments."
"I only accept PayPal payments made with account balances or bank account transfers."
"I only accept PayPal if the bid amount is greater than $15.00 USD."
"I only have a Personal PayPal account and only accept those kinds of payments."