I feel like such a loser

Ive had bad experiences using offerup. But when my sibling uses it her purchases are phenominal. I wanted to buy a vacuum but they are expensive and im not really working…. i bought a vacuum on offerup for 20 bucks. He tested it out on concrete and it picked up the leaves… when i used it on my carpet it made a weird noise and a part fell off! What hurts is that i already knew i have bad luck with offerup but i let her talk me into using it again. What am i doing wrong when i buy on offer up? How do i make sure i don’t buy junk?