Peer reviewing is typically unpaid in all cases. People are donating their time and the result of their hard research work to for profit businesses because it's the only way to get ahead (prestige).
My own rule of thumb is that I have to to three peer-reviews for every one paper I publish, since my paper will have three reviewers (usually). That way I can stay at review/submission equilibrium!
I actually got sent my first outright awful paper recently, and there wasn’t in the end much of an onus on me. The flaws of the paper were so blatant that I could simply tell the editor that the entire premise was unsound without having to go into much detail, and the editor understood.