Botting on the marketboard. Impossible to sell anything.

[Jojoya]

The perk of bots is that if you post something and are immediately undercut by 1 gil, you can repost a few times to verify it's a bot. Then do a super low undercut, wait for them to undercut you by 1 gil and buy up what you want/need, forcing them to take a huge loss. I got 10m gil items for just 10 gil before this way.

That was someone who didn't know how to use their bot.

Most bots have a price floor. They will not lower their prices below that floor even if undercut. That price always represents profit to them. They might not be making as much as they would at the higher prices but they're also not taking an actual loss.