Pay rates have nothing to do with etiquette. There's token markets and pro-markets and semi-pro.

I've sold more than one reprint. But I've looked for publications that take them, and informed them that it is a reprint. It's just a simple case of following the guidelines. I always ask if there's no clear info on reprints.

Btw, I've been paid pro-rates for fiction and you can't make a living off it just doing short fiction.

I'll make more money off the average non-fiction article, and it's usually far shorter than a fic piece.