I have never known this to happen

Why would you care? In my experience, idiocy in adults is almost always incurable.

I shouldn't really, I know, but it is a bit galling when you see an apparently genuine question from a learner, and you take the time to do a bit of research, only to see your post downgraded for no apparent reason.

I understand. Unfortunately, one needs to develop a thick-skin around here.

It's not like that on English Stack Exchange!

This site has a long history of member abuse, which began in political threads and spread throughout the topics.

The threads about Rainsoft water softener pumps seem fairly all right.

No clue who down-thumbed you, but I appreciated learning something from you, so I went back and up-thumbed all of your posts on this and the previous page. I didn't feel like you were being snotty or anything.