Unfortunately, I don't think those would help, and they might hurt.

Your first suggestion doesn't address paid reviews. Usually the scheme is "buy it, and we will reimburse you with a little extra on top after you leave a review."

Your second suggestion would probably bias towards fake reviewers. It's pretty rare for someone to get paid just for one review.

One of the hard things to realize is that paid reviews are written by real people. Most of them probably know they are doing something shady, but not all - some think this is a legitimate marketing interaction. Many of them also leave real reviews for stuff - including negative reviews. It's generally not actually bots writing reviews.