I work at a retailer and pretty much all mods get removed. If we sell a game and some dollar store mod comes loose, that's a phone call for something that shouldn't be a problem.
Now every TZ I do gets gumballs [no black - whoever ate a black gumball] but other than that can't think of any others I normally do. I guess LEDs are a mod so we do those on request. Tasteful. No colored GI EVER!!
Like most other reasonable people on here, there are GREAT mods out there. Tron arcade cabinet and ramp lights. Hell even HOOKED pop caps greatly enhance the look of a game. But this dollar store sh!t with leds inserted that run thru and clip on with alligator clips really grinds my gears.
And the price of some of them are jaw dropping. Pinballdecals.com :O