I dunno, these cars already suffer quite enough from the 'It's cute/Hot Wheels/Is it a kit car?' syndrome. Tasteful customizations, like getting rid of the turn signals in the front, filling in the faux fins next to the tail lights on the Elise, and understated front splitters work nicely.
It's REAL easy to go over the top, approaching ricer/Fast & Furious cartoon caricature status. Cannards, picnic table size wings, multi-element diffusers sticking a foot out of the back of the car...more often than not on cars that are functionally used in ways that don't require ANY added downforce components only make these small cars more cartoonish.
And lately folks have started putting roofs with scoops on Elises...
That said, I'm from the "It's your money, it's your car...do what you want" school. My last Europa, restored to the nth degree, was painted in a color other than original, so in some schools I'm a blasphemer. I get it.
For my own part, I'm just underwhelmed by cars that look like a JC Whitney catalog exploded on them.