On a somewhat different subject, I'd like to add: There are only two
polite types of potluck gatherings. One is the type where the "host"
and "guest" don't really know each other - such as a community
gathering at a church or a park. In that case, of course, you, as the
"guest," are not expected to reciprocate in the future by inviting the
"host" to your house, so helping out by cooking and bringing your own
dish makes sense. One usually gets the "invitation" by a mass mailing
- or by street flyers.

The other is where there is no "invitation" at all, because the GROUP
decides to have a potluck, not just one person who then inflicts the
idea on everyone else, who may or may not be annoyed at an
"invitation" to a party where no real hospitality is being offered.
(Even if you're really poor, chances are you can serve ice water and
crackers AFTER the guests had lunch or dinner elsewhere.)

The only exception I can think of is the case where the "host" is
bedridden or something similar and therefore will never be able to
come to my house. In that case, I consider it only fair to bring
something, even if I'm not asked to do so.

Trouble is, too many people - who were likely surrounded by shakedown-
artist families as schoolchildren - see NOTHING wrong with sending out
"invitations" to parties and making it clear the "guests" have to pay
cash to the bartender or pay for their own food or theatre tickets,
just because the "hosts" want to live above their means. Thankfully,
it is perfectly polite not to RSVP to such appalling messages, just as
one does not have to RSVP to fund-raiser "invitations" from
strangers.

Lenona.