Why is &amp such a common spellcheck typo on Audiogon

It’s not a typo; it is an artifact of how the page is encoded and how the browser interprets the coding.

"&" (without the quotes) is html notation for an ampersand. Depending on how the site encodes the page, and I believe also depending on what browser (and what revision of the browser) is being used, the result may be that "&amp" appears when the page is viewed, rather than "&" which is what the poster wrote.

Regards,
-- Al

Thanks Al. Great explanation.  Code within codes.  Annoying.

To wit: https://forum.audiogon.com/discussions/should-manufacturers-provide-circuit-schematics-parts-list

I tried to edit the title to remove the “&” without any luck.(It includes the coded “&” in the Forum listing.)

Yep
&amp did not make me think of ampersand.
i was thinking amplifier and wondering.
A strange bit of word processing.