Guys, it's all a question of taste. Some hate Nascar. Some hate F1. Some even hate GT! We shouldn't be arguing about this, because there's something for everyone in the crowded world of sim racing.
For example, I love all kinds of car racing, so everything is fine for me. You just have to focus on the most important characteristics of each one.
I love the graphics, the cars and the balanced gameplay of the GT series, specially on the hardest races, which are a great challenge. I love Geoff Crammond's GP series games, for their great sense of realism (when driving on the wheel with NO HELPS ACTIVATED), the sounds and sheer speed.
I love the Need for Speed series for the graphics, sound and pure fun of playing it, specially in 2 player mode.
I love Live for Speed, for it's extreme approximation to reality. This is what I call "Flight Simulator on 4 wheels". The car reactions are fantastic and extremely close to reality (put a RS Shifter and Pro Pedals and it's almost the real thing).
And (people are gonna kill me after this one) I also love the Papyrus Nascar sims, for the impressive array of racing characteristics and the realistic feel of driving a 2 ton car over 180MPH. 3 cars side by side give an incredible rush of adrenalin, specially with a good set of speakers (makes the floor shake).
So, instead of saying what is good and what is pure s**t, try to spend some time with each one and find its best qualities. That's what matters, after all.