Whaaaat? Piranha is at 72% on Rotten Tomatoes. Maybe it was a bit higher at some point, but I find it very hard to believe that it was once up in the 90% area. In fact, if you look at the RT review by the date they were submitted, the page with the oldest reviews has 4 rotten reviews and 11 fresh ones, for a rating of 73%. I see no way this film was ever up above 90%.
It is also worth noting that there is nothing wrong with critics reviewing movies within their genre and what they are trying to be. Heck, I think that is far preferable to pretending that every movie is striving for Oscar-winner standards. By that logic, The Avengers and The Hunger Games, which will not even begin to be in the running for any non-technical Academy Awards, would get bad reviews.
You need to know what kind of movie you are getting yourself into before you buy a ticket. I believe people should look at what critics (and friends and other people) are saying to gauge whether a movie is of quality WITHIN THAT GENRE. Heck, most critics are falling all over themselves over The Master, but if you are someone who likes action, sci-fi, and horror films you probably are not going to like it. Just because the critics say it is good, does not necessarily make it a good movie for you unless it falls into the realm of films you seem to like.
Of course, to me the irony of all this is that I know CF quite well... we were at Duke together... and Piranha is his kind of movie. I am sorta surprised you did not like it at least a little bit. If you left early, you got to miss the gratuitous scenes of the little toothy fish gobbling up Jerry O'Connell's... well... member... as well as his character's reaction to said munching. It is one of the finest schlock moments in recent movie history.
-Jason "if you want to see a good Piranha movie,
check out the 1978 one. If noting else, it served to launch the careers of John Sayles and Joe Dante" Evans