Attack IVs are not bad on physical attackers, as they need them to reach maximum damage output. On any Pokemon that isn't a physical attacker (special attackers, walls, etc), 0 Attack IVs are good because of two things: Foul Play and confusion. As both go off the Attack stat of the targeted Pokemon, the fewer Attack IVs a Pokemon have, the less damage they can do.
Special Attack IVs are completely useless to worry about, you just want 31 at all times except in a few very niche scenarios, none of which are worth mentioning, as none are viable competitively.
Hope I hleped!