Is it a bad idea to buy a used car that isn't completely stock?

So I found this 2006 Acura TL at a dealership nearby. It's an official Acura dealership that has great reviews all around. However the car just seems shady to me. It seems to be in great exterior condition, and it has low miles (50k), however it looks like the previous owner did some work to it. I'm leery of used cars that aren't stock. There appears to be a body kit on the exterior and tinted windows, besides that the car isn't lowered and the wheels and rims appear to be factory original. There also appears to be a button missing from the door panel in one of the photos. I'm worried about the previous owner altering the factory suspension and possibly doing things to the car that may be prone to failure later in the car's life and basically not taking proper care of it. This car seems perfect for me, matches my exact price point, low miles, has all the features I wanted, has the color I wanted, comes from the Honda/Acura family which is of high importance to me. However I want this car to last a long time and I'm just leery about the previous owner tinkering with it in any way. I value used cars that were simply driven; not tinkered with or altered in any way. Seems like a great car but these things are holding me back. What do you think?

When it comes to modded cars, I usually assume that the previous owner(s) focused more on aftermarket parts instead of general maintenance unless there are physical documents/records indicating that they did maintain it. If there isn't any documentation of full service history, don't waste your time, no matter how tempting it is.

This is why modifying a vehicle often decreases its resale potential.

It depends on how it was modified. If it's cosmetic stuff only, who cares. In your situation, you should take it to a reliable mechanic to take a look at it, just like any used car.