My list or reasons I go hard against ads, even though I can appreciate quality ads that can serve a legitimate purpose:

1) tracking me across in serval ways, only making me more fanatical about it by selling my information and activity to who know whom. 2) malware/virus injections … it still happens way too often. 3) garbage ads; for garbage products, products/services I just purchased, or the infamous scam ads to defraud people.