Here's something you may not know, the *-insane dictionaries, which are giant, are functions of OCR output and are known to contain lots of errors.

I found a few earlier this year and I was going to file a bug so I did some research to find out this is a known and expected behavior.

If the computer say reads stubborn as stubbum, the smaller dictionaries are the ones that have cross checked and filtered those out. The insane ones do not. It's a good name. "Lack of sanity checks"

Here's an example word I found, "suabilities". You'll find it only on wordlist sites that used this wordlist and I guess, now here.