re: How bad of to run trolling motor in saltwater?

I've run freshwater MK's on my boats for years due to the black color matching better than white, it's a little more maintenance to keep the corrosion gremlins out but nothing over the top. I've had a couple warranty issues and they've never asked if it was run in saltwater, I've heard people make that claim before but have never heard of it happening. The one glaring issue is the coating on the lower unit of the motor always seems to come off, I've seen the same on Riptides FWIW, I rino line my motors right off the bat now and it takes care of that issue.