Is getting paid through PayPal really completely free? Or does PayPal take a fee from the sitter?

Paypal is free for the sitter. Rover takes care of any fees. You get the full amount, after Rover deducts its fees.

I've been using Paypal for more than 10 years. I've never had a problem. Be sure to go through the process of having Paypal verify your bank account. Paypal will deposit a few cents into your checking or savings account. You tell Paypal when and how much was deposited and it is done.