Personally, I think some people look down on the foriegn econo-cars for exactly the reason Zmoz stated, you're putting yourself at a big disadvantage to begin with. Besides this, these cars were mostly intended for economy, not speed. There are exceptions to this, of course, like the Celica or RSX-S, but Civics, Neons, Cavaliers, Corollas, etc are all econo boxes. The old muscle cars of the '60s and '70s, plus the Mustang, Camaro, Firebird, Corvette, etc are already built for speed. Modifying them can give you a real monster, which is what guys like.
Given that, however, the majority of modded econo cars I've seen have been done poorly. They put some AWFUL looking wings and body kits on the cars, as opposed to some of the more tasteful changes you see from the professionals on TV. In addition, the loud mufflers sound awful. It's not a nice throaty rumble that a V8 would produce, it's noisy and annoying and doesn't sound nice most of the time.
I do think it's possible to do this right, however, and I've seen some really well done vehicles. But those are the ones that have had some real thought put into them and are designed by people who know what they're doing. If everyone that modded their cars put half as much thought into them beforehand, I think there would be a lot less ill will from the older folks.