Phil had a post about this already and I talked with with him Sunday about BS laps. In a nutshell the more unsusual the car/theme - the older the better - basically no problemo. Newer the car (i.e. late 80's or newer) no matter how well documented it is, you just may be on the BS radar. That is no gaurantee you'll get laps, but more likely than a pre-80's car.
If you look hard enough and if you're at the right place at the right time, you can get killer $500 cars, I know you can, but if it's just "too good a deal" or was modified by any previous owner, be prepared to have some BS laps. I have been to 3 Lemons races with an honest-to-God $500 car and have been hit with BS laps each time, just this last event at Thunderhill was the most yet. It is what it is. Turns out it didn't matter cuzz we suffered a terminal brake fluid leaking problem anyway, we DNF'ed
I didn't like being hit with the laps and worse yet being called a cheater, but once we got hit with the BS laps, our goal of finishing in the top 20 obviously changed, but our goal of no black flags and going faster then we did before at Thunderhill, meet new and a wee bit twisted people like us and party hardy Friday and Saturday night were all met!! Actually we did recieve 2 black flags - one on each day - but since they were "mechanical" when the brake pedel hit the floor and the car flew off track, Phil just said go fix the damn thing before you go back on track, so I don't consider them "punishable" black flags. (i.e passing under yeallow, spins, 2-4 wheels off, contact, speeding in the pits, etc.)
Anyway BS laps can be an unknown factor at a Lemons race, no doubt about it. Some people that get 'em leave ya scratching your head as to why and others get essentially 0 and you wonder how that was possible. I talked with a fellow driver that has participated in 16 Lemons races and he cant figure out BS laps either.