Meh button etiquette

jds2001 thought this was worth mentioning said
7

So probably a FAQ or something exists, but I’m way too mediocre to look for it. What’s the protocol for Meh button clicks? What if I actually buy the item? It seems that I shouldn’t click the Meh button since I thought it was worth at least whatever price it’s being sold for (and therefore not Meh), but I also then lose the streak. SO MUCH CONFUSION!!!