Nothing is perfect in this world, least of all on the internet, so it doesn't surprise me that large web organisations like PayPal are involved in legal disputes. We can only comment on our own experiences, and if some of those are negative, then that adds to the information users can read up on, so they can make their own decisions.
But I do have a few comments about your post.
1] The http://www.paypalwarning.com/ web site you linked to raises a WOT, (Web of Trust), advisory about that web site's trustworthiness;
Not many comments to be fair, but one suggests the web site distributes spyware. I always worry when I visit sites where my WOT Browser security plugin throws up a warning.
2] That same site. Did you follow the link at the bottom of the page, the; Click here for our PayPal alternative?
It seems the alternative is a "Real Merchant Account". A competitor to PayPal?
That might not appear suspicious at first glance. I mean, there are always competitors, right? Only, that WOT scorecard link above also includes a Whois option, and following that I see that the Whois for www.paypalwarning.com has a 'Domain name' of Merchantinc,com, and Merchantic.com also owns the PayPal alternative site of http://www.merchantinc.com/
So, a competitor telling us how dangerous PayPal is?
3] The Google link you gave. The first link I tried http://www.paypalsucks.com/ gives similar PayPal horror stories. But guess what? The option on that site for Click here for the #1 PayPal alternative, sends me to... you guessed it, the same http://www.merchantinc.com/ as before.
It seems www.merchantinc.com has been busy with it's 'PayPal' alternatives.