If the words are slurred and the lyrics you can make out often don’t make sense, it’s Eddie Vedder (Pearl Jam).
If the words are slightly less slurred and it sounds like he’s trying to sing through a hangover and a mouth full of jagged marbles, it’s Kurt Cobain (Nirvana).
If it’s somehow monotone and soulful at the same time and the backup vocals sound like six of the same guy singing at once, it’s Layne Staley (Alice in Chains).
If it sounds kinda like a dark and spooky Disney villain but also kinda like the guy at the biker bar who might kill you, it’s Zakk Wylde (Black Label Society).
If it goes from melodic singing to throat-murdering screaming in the span of one word and sounds like he’s gonna kick the world’s ass, it’s Dave Grohl (Foo Fighters).
If it goes from melodic singing to throat-murdering screaming in the span of one word and sounds like the world has kicked his ass, it’s Chris Cornell (Soundgarden/Audioslave).
If it has the deep grittiness of Zakk Wylde, the slurring of Eddie Vedder, and lyrics that make you wonder if it’s about sex or murder or both, it’s Scott Weiland (Stone Temple Pilots).
BONUS: If it sounds like an alien trying to mimic the patterns of human singing while sacrificing all semblance of lyrical meaning in favor of nonsensical rhyming, it’s Anthony Kiedis (Red Hot Chili Peppers) and he doesn’t really belong on this list because no one mixes him up with anything.