RT has Black Panther as their #1 movie of all time. The fact is, people have learned to inherently train themselves to use certain review websites. https://www.rottentomatoes.com/top/bestofrt/
My current rules - Anything over an 8 on imbd is a must watch if over a year old. If a comedy/action movie over a 7 is fine. For less than a year old I read reviews, and decide how invested I am in watching it. Fantastic Beasts 2 tanked, but I watched it anyway and enjoyed it.
Similar for me, but more forgiving. Especially for horror which I enjoy but IMDb raters don't seem to the same. In general, anything below a 6 I'll maybe reconsider, or 5 or so for horror.
My current rules - Anything over an 8 on imbd is a must watch if over a year old. If a comedy/action movie over a 7 is fine. For less than a year old I read reviews, and decide how invested I am in watching it. Fantastic Beasts 2 tanked, but I watched it anyway and enjoyed it.