As a followup, I was finally able to get rid of that plastic/hot metal smell from the Ninja air fryer. Here is what I had to do:
Put the following pyrex bowls in each basked containing:
- apple cider vinegar and garlic.
- mixed baking soda with water.
- half of a hot dog.
Heated both baskets to 400 degrees via multiple cycles of 3 to 6 minutes for each step until liquids were mostly evaporated, and the hot dog was pretty much nuked.
That seemed to do the trick. Been cooking frozen french fries with the air fryer and they have no unusual smells or tastes about them. Actually they are rather yummy.
I might get more adventurous over time. I did try breaded fish paddies in one basket and french fries in another, but the fish didn't look anything at all like what was pictured on the box. Not sure if that was my fault or just overly optimistic advertising from the Mrs. Paul's marketing department.