I use PayPal quite a bit, mostly to pay for ebay purchases. One thing that annoys me about it though is that the site sneakily always tries to get you to pay direct from your bank account (which you have to add to your account), rather than use a credit card. There's no way to set a preference, the default is always for your bank account, and the 'funding options' link, which you need to click on to switch it, is easy to miss, in a small font.
Even when you click on the link and switch to credit card, it still has one last go at dissuading you: "before deciding to fund your payment with a debit or credit card, consider the benefits of paying with your bank account".
Clearly, the costs incurred to PayPal are higher for credit card and debit card transactions (I think it can go up to 2% or 3%), but why not be honest about this or pass the cost (or the saving) to the user? Whilst PayPal tries to sell me the benefits of a direct bank transfer, the benefits of using your credit card are better secruity (you can ask the bank to do a 'chargeback' if the item doesn't arrive, which PayPal/ebay can do nothing about), as well as the 1% 'cashback' bonus I get from using the card (which I always pay off in full at the end of the month).
So PayPal, stop being sneaky and start being honest!