If it's below the 70s range, it moves to "is there a demo to try first?" category. Some of my favorite games have been low 80s/upper 70s in terms of crititcal response. I can still enjoy a game with some deep flaws. That being said. If you're looking at a sub-70 score - I'm not paying $60 as the admission price.
Used baby! :)
EDIT: As an answer to your second question: anything 90+ takes me off of the fence and into Buy-Land. If I wasn't at least thinking about it before, I'm probably not going for it either way. Reviews have some sway, but I put personal interest in the type of games way ahead of that.
Retro Tech Select - My Youtube channel. Covers throwback consumer electronics with a focus on "vid'ya games."
Latest Video: Top 12: Best Games on the N64 - Special Features, Episode 7
