You really can't trust reviews at all. The best advice I can offer is to mentally average scores across two or three pages and use that to decide whether scores are being gamed or not. No product will produce 100% satisfaction. If you see something with 100% 5-star reviews it is almost certain it is being gamed in one way or another. 1-star reviews can be hard to evaluate. I know one seller who had a massive 1-star review attack launched against them. Their revenue went from tens of thousands of dollars per month to nearly nothing within 30 days. Horrible.