Yeah VirusPil, that is pretty much the exact way I am rating movies right now... almost two years ago I started to rate everything I watch on imdb which is also a ten step scale.  Like you I rarely rate anything under 3 but that is probably because I can recognize a lot of bad movies before I see them just from looking at the actors, write-up  and art on the cover.  I can say that I have rated about 10 percent of the movies I've watched as a 5/10 or lower in the last couple of years and I've even given out a couple of 1's! lol