Andrea wrote a few days ago in reference to our Good Word squalid the following:
“In response to the squalid Good Word: the minute I read in your text that squalare meant meant ‘to be covered with a rough, scaly layer, be coated with dirt, be filthy,’ I thought of scales and wondered whether the concept “squalid” is related to fish scales. [This] would also make sense because of the identical word for a large fish in Latin squalus and filthy. So not that fish become stinky, but that being covered in scales when you are a fish and to be so dirty that you are scaly (when a person) are similar.”
In fact, I can mentally picture a squalid house falling apart like fish scales fall from a fish, so I am in sympathy with Andrea’s connection. In fact, I tried to suggest that without committing myself to a firm connection since I could find no etymologist who would agree with me.
The problem is that if this were the case (and I believe the similarities too close for it not to be), it was the case before Latin developed from other Italic languages and we have no record of words that are ambiguous between “scaly” and “squalid”. So we have to rest on “in all probability”. That is as far as even I have courage to wander.