Attempt at a rating chart:
4.5 to 5 stars: Movies I think are really great and probably own, because I want to rewatch them.
3.5 to 4 stars: Movies I may not own or have watched in a while, but remember really enjoying the last time I watched them. 4 star movies might be really, really good ones I've either overdosed on watching, or for whatever reason have no active desire to rewatch. Generally willing to rewatch if I'm watching with someone else, or if I'm sick and they come on TV or something.
3 stars: Movies I liked. Probably won't watch again, unless I'm watching with someone else, though. Occasionally movies I may have rewatched a bunch when I was significantly younger.
2.5 stars: Movies that I either have virtually no memory of whatsoever, or movies that were an entirely neutral use of the time spent watching them. Would prefer not to rewatch.
2 stars: Movies I didn't turn off, but didn't really like - I wish I'd done something else with my time.
1.5 stars and below: Actively disliked, probably turned off if I had the opportunity to.
*Occasionally* would be willing to watch a particular "not interested" that fits the category as a "bad movie night" type deal.