I think swapping half-used paint is a bad idea most of the time
Last week I traded a nearly full tube of cerulean blue for someone's "barely touched" alizarin crimson, but it was completely dried out and crusty around the cap. Maybe I'm the odd one out here, but hasn't anyone else had more duds than wins with these trades?
3 trades I've done on Facebook Marketplace for art supplies, 2 were basically garbage. Honestly it's the same pattern as those "like new" electronics listings where they leave out the cracked screen in the description. Ngl people just have different definitions of "barely used.