Quote Originally Posted by Deadly View Post
True, Dash's abode was never the hardest one to explain (that honor probably goes to Fluttershy), but that doesn't exclude my theory, and I like the idea. It's also worth noting that Dash appears to be the only pegasus in Ponyville with a cloud house of any kind.
It's a giant tree. Given she's apparently a veterinarian and a pet shop, she should be able to afford her home. It's not that big either. Probably smaller than the library.