Had a buddy who went through the same thing with a chef in Austin. Guy told him "salty like the ocean" and he dumped in half a box of Morton's, then had to toss the whole pot and start over. Turns out the chef meant like a light ocean breeze, not the Dead Sea. My friend still measures his salt with a spoon now, out of spite.

Is losing fifteen bucks really worth a whole rant online?

Bringing trays to a game cafe is different from bringing them to Mike's basement. At a cafe, you're using their tables and their space, so pulling out your own gear can come off like you're saying their setup is bad. Just ask the staff or whoever runs the night first, since some spots already have trays on hand.