It’s not really a pet peeve but it is definitely an annoyance for me to hear something mispronounced, especially on the radio.
A few years ago there was an ad for something in a nearby town. The name of the town is Alton pronounced All (everything) ton (weight). The announcer called it Al (man’s name) town. It really grated on the ear.
When I hear things like this, I wonder if the copy writer or the ad agency did any research into how to properly say something. Maybe it’s a regional dialect but if you really want to sell something to me, make sure you pronounce it correctly.