Body Rust

Both of the photos show classic sun damaged paint failure. Neither look unsalvagable and with proper prep can be repainted. The whole roof will need a respray. On the plus side, the Tacoma roof strips are a good place to cut in. Sand to bare metal, treat any rust spots with picklex or POR15 metal prep, 2k epoxy primer, body work any pits or dents, epoxy prime over any filler, sealer, 2k urethane color coat, 2k clear. After the clear cures for a good month, apply a quality straight wax regularly.

 

Same thing down here on the gulf coast. If you get within ten miles of the water it's almost like the salt is in the air and then it settles with the dew... combine that with the intense sun and you get what's in the OP's pic. It was even worse back in the late 80s/90s when they first started using clear coat.

Luckily I'm 50 miles inland.

 

The closer your vehicle's color is too black, the more sunlight it absorbs. The closer your vehicle's color is to White, the more light it reflects. Factors such as sunlight, proximity to large bodies of saltwater, living in places where the road gets salted because it snows, not garaging your vehicle on a regular, bird turds, and other things will make your vehicle rust faster than normal. If you have rust, and you cannot sand it completely down, then the metal has to be cut out and replaced, then properly sealed & painted, otherwise the rust will continue to propagate. If you live in the areas that get salted regularly, then it is great idea that completely clean your undercarriage and apply undercoating periodically.

 

It’s on the roof where only you and Shak see it. I’d rattle can it.