Yes, some PTC traffic can convert if the offer is what the person is interested in. But it's all suspect at best. People are clicking because they want money, not because they are looking to buy.
Yes, if an advertiser is advertising on a PTC site, then they should know what they are doing. It is the advertisers that are advertising on a search engine, and a PTC site is sending it's members to click on ads from a site they own, or a member owns. That is 100% fraud.
I'm sorry, but you are 100% wrong in this. They are the ones doing the actual stealing, even if they do not understand this. If I tell you, "That is my store, would you bring me something I need from the shelves?". You go into the store, take something and walk out because the clerk was distracted and did not see you. Are you not a theif, even if you have been tricked into stealing? Perhaps you are not a bad theif, but you are still guilty and may be punished. For sure the store clerk would have stopped you.
So too would the advertiser or search engine stop you if they knew. Just because they may not know what you or the PTC site is doing does not make it right, only an easy crime. This is my opinion on the matter. Any rationalization or explaining will be falsehood when examined in light of what the advertisers or search engines think. Do not deceive yourself as so many have that it is ok to steal. You can do it if you want, but it is wrong and at some point a price will be paid by those that knowingly do so. Also my opinion.