In my cranky yet partially tongue-in-cheek opinion,
explain it like a bicycle with training wheels:
The Disney characters are the training wheels.
Donald Duck and Goofy are the wheels, and you should be embarrassed to associate them with anime. You want to 'grow out of them' as quick as possible.
So you transition to Ghibli studio stuff (Miyazaki+Disney=still too kiddie/cheezy) and then to mixed production (half-breed) works like Transformers or Vampire Hunter D - non-Japanese studios or creators still partially present in the mix, that's like when you raise the training wheels up a notch or two so they're not always on the ground.
You could then call English dubs another notch up (or down - depends on your opinion.)
Once you're on-board with subtitled, fully-Japanese animation: Gonzo, Madhouse, Pony Canyon, Broccoli, Studio Pierrot, Gainax, ... and you're starting to pick up vocabulary, grammar, and cultural notes that won't work in English - the training wheels are off.
Kudos, a gold star, and a pair of snappy-looking Spandex bike shorts if you made it through this phase and can name some of your favorite seiyuu, but cannot name a single English voice actor.
Then when you graduate to watching raws - that's a unicycle!
PS: Air Bender and Invader Zim would be tricyles: 0% Japanese content = not even beginning to be anime.