Knowledge is rarely a good thing but sometimes it actively reduces your quality of life. Take coffee as an example. Coffee is an accepted addiction, you cannot go around going 'Sorry I am not with it yet, I have not had my Vodka' but the same excuse for coffee is nearly mandatory as so many of us need coffee to function.
Some strange people learn about coffee though and as a result they no longer can cope with Nescafe instant. Next they notice burnt flavours and incorrect coloration in coffee shop coffees and an epic impossible quest for the 'God Shot'. Expresso starts to ruin their lives.
If you are addicted to a drug becoming snobby about that drug is a really bad idea. You don't see crackheads demanding only the finest Columbian devils dandruff in their rocks. Yet coffee addicts get themselves addicted to a drug then try and make sure they are miserable almost all the time they take the drug.
A normal coffee drinker gets a mild amount of pleasure from instant and when they go to a coffee shop get a fair amount. Someone who has gone to the trouble to learn about coffee lives in a constant state of disappointment except the rare occasions the world champion barista they have taken two hours to go to does not do something almost imperceptibly wrong.
The worst thing to know about I think is fonts. I don't even notice fonts but I have friends who can spot the bad font in a street with 100 other signs. You never hear them happy about fonts all they seem to bring is pain. The entire world just seems to become an annoyance to someone who knows how text should look.
Do you have any nominations for things you are really better off not knowing?