One good way to detect an attempted fraud of your Paypal account is to look out for things that just don't make sense to any normal person.
A good example of this is, say you have been doing business on Ebay and using Paypal for a good number of years now, have hundreds of successful transactions under your belt, and then it happens.
You get a message supposedly from Paypal that says something like: Your Paypal account has been limited or For security purposes, please link a credit card to your PayPal account to confirm your address. We won't charge your card unless your PayPal account doesn't have enough money to cover the payment.
Now, you know from many past transactions, that funds are available in your Paypal account and your valid credit card is already linked to your account, so, the above message could not possibly be a valid message from Paypal. You have just detected an attempt to gather your credit card information by a party other than an official Paypal officer.
This scam is perpetuating on a continual basis and seems to be increasing in both volume and frequency over time. Contacting Paypal and Ebay does absolutely no good. They assume that you are confused and need to reread the "terms of service" agreements of their respective organizations a couple of more times to get your head straight.
Best thing that one can do when such a message is displayed is to find another auction service or another payment service, start over with a new user name and a new password, and don't look back. Paypal will not release your funds, They are gone. Ebay will not moderate a complaint against Paypal, as Paypal is owned by Ebay, and, therefore a partner to the theft of your funds.
Best you can hope for is devine intervention, but, don't hold your breath on that suggestion.