On the other hand, if you bought a PS3 from someone who didn't legally own it in the first place, it's not a valid sale, and you don't really own the PS3 either. You're not even entitled to automatic compensation if the rightful owner takes back the stolen property.
Incorrect. The bona fide purchaser for value without notice rule is applicable here. If the purchaser buys an item for non-trivial value (ie something that could be considered a real price) and does not have actual or constructive notice of a third party's title (which is to say that they did not know and could not reasonably have been expected to know about the third party's ownership) then they acquire good title and the original owner cannot enforce their property rights against the purchaser. The original owner is stuck with having to sue the thief for the value of the item.
Of course if you buy a PS3 from some guy in a pub with no proof that they own it, then you have constructive notice that someone else might own it. If, on the other hand, you buy an book from a reputable book retailer, you are entitled to rely on the retailer's implicit claim that they own what they are selling you. You can not reasonably be expected to check whether Amazon actually had the rights to sell 1984 so you acquire good title.
Of course in this case copyright law is also applicable and may allow authorities to seize infringing copies but the parent posters points were purely on the issue of property law and the parent is incorrect.
Standard disclaimer. I do have a law degree but I am not a lawyer.