$3900 vs $2500. There's the difference.
The 87' is nice because they started to use the 2nd gen headlight motor's which are far superior. That 87' doesn't have a rear trunk carpet which would make me wonder if he has one.
I've read about 'jasper' engine's before but don't know if that means just a rebuild, or something else.
The 87 seems to have a fiero enthusiast but doesn't have a cleaner look. The 86 owner is probably someone that likes the car, but doesn't know much about it.
In the end it all comes down to you.
Take a corner at 130, and you'll understand the term "dirty."