As said above you can have solid appies :) my mums has morgan in her ancestry.. mine goes all way back to indian horses! There are a lot of different shapes. For example If you compared the most of the american appaloosas to the English ones you'll see a lot in america now just look like spotted QH :(
Look at the hooves...striped hooves are a 99% way of telling if she has appy in her. I know of a 16.2 hand solid black appy that you would swear is a fresian but she is registered appaloosa all the way and her momma was a leopard.
My grandpa has completely solid 16.2hh Appy gelding! No mottling, no striped hooves! Nothing! His full sisters are almost completely roaned out, and stand at 15 hands flat. Genetics are weird! But yes she is probably an appy!
Even at world shows, 50% or more of the classes have solid appys in them.
Ive ridden a 16.2 80% foundation App that was red turned grey/white and has minimal mottling. He was a nutty horse, but all App.
Im currently working with a 16.2 solid red mare, not a sign of App at all; no mottling, no spots, no cap, nothing. She isnt even built like an App, she looks like a warmblood TB cross with forearms as thick as my thigh and what a neck shell have when she gains all her weight back. Smooth mover too. But her papers say that she is half foundation App and half Appendix, and her last baby was LOUD App coloring, a black leopard. She was being used to breed for colored sport horses. Supposedly solid Apps throw really loud colors in their foals, and I've heard the same thing of solid paints too.