Well from what I've experienced when I played -dont know if it's changed already-, was that impossible words still counted. Maybe some foreign words even. Words who looked like gghah or something
But then again, I stopped playing it for a while after I got annoyed by the impossible words.
Lolwhut, the list of words is from SOWPODS. You can google and download that list, if you like (not sure if I can provide the link here...). And yes, there are some strange words in it.
I like much better Dino-RPG because this one is about exploring, while Popotamo is about doing the same thing over and over again...
DinoRPG is my favorite online game though i like to play Popotamo but as i'm portuguese when i get english speaking people on the game it gets really hard to get even 5points......