No I don't think so. Good question!
I watch movies that I am interested in, and not whether they are rated as anything. The only movies I do not like are violence/action/superhero however the classifications in Australia anyway, do not show these unless they are really violent when I guess they would be Adults only.
As for ratings, yes, I do take notice of this if you mean like they have won an Oscar or whatever -i am more likely to see a film if it has won a lot of awards, however not sure if this is also what you mean in the question.