2006 Mustang Gt With Aftermarket Bluetooth

[fd06stang]

I test drove a 2006 Mustang GT with low miles and the only thing I didn't like about it was that it had an aftermarket Bluetooth system installed (possibly an alarm as well, dealer didn't know). It has this random button on the dash that kind of sticks out. I passed on the car at first but I keep thinking about it and wonder if this is anything I should be concerned with?