Nuvi 755 gooey back

I'd personally try cleaning it with rubbing alcohol. Start off on a corner and see what it does. Don't rub hard, just glide over it a bit very lightly. I noticed this stickiness as well with this model's grippy finish. But my 765 is no longer used and pretty much just sits in the car's trunk as a backup unit, making a brief appearance for map updates.

I've also noticed the same thing with certain models of Microsoft mice (older models with grippy areas). In the case of the mice, cleaning (even with just mild dish soap) eventually started removing the grippy surface.

I think this type of finish just eventually starts to break down due to hand oils, etc with really no way to stop it.

Good think I always store it in my desk drawer. Hot temperatures are usually bad for electronics.

I've had to re-foam any number of speaker surrounds over the decades that I've lived in Florida. Something - probably the high humidity - affects the rubber surrounds and eventually they degrade from the condition. I wouldn't be surprised if this is a similar phenomena to the 'sticky, melting dashboards' that a number of vehicles have suffered from in the past few years.

Likely. I also note that my Uniden police scanners came with these little square rubber stick-on feet for the metal mounting bracket. When I set the older scanner on my dashboard for long road trips it is something of a battle to peel it off as the rubber likes to stick to the textured plastic dashboard of my Prius.

My spanking new scanner model has those same rubber feet and they are not so "sticky"--yet.