Bottom feeder is a well used term in the AC forum and maybe others.
Refers to passengers who book the cheapest flights and maximise upgrades, lounges and all the perks for the lowest possible price.
Only pejorative is you choose it to be.
The AC Bottom Feeders of old were a proud bunch.

My reference to Bottom Feeder here is those of us who buy a cheaper than business class fare, upgrade it for free, subjective but not pejorative, and use all the perks suck as a swanky lounge restaurant.

Ironic part is we are debating something that will never happen!!!