You know, I'm mostly forgiving when it comes to flows, but there are some rappers who sound so awkward that it grates me. Back the late 90s, early 00s, I really struggled with Talib Kweli and Sir Menelik. Jeru, after Sun Rises in the East, fell the eff off with his flow too, nearly ruining the dope tracks that Primo cooked up for Wrath Of the Math.
But, for me the most irritating, are the cats who in 2009 still spit those super-scientifical rhymes where they try to cram 30 syllables into one line, spitting conspiratorial and/or science-fictional non-sense. Those cats are still stuck in the Company Flow-influenced, East Coast-underground era of the late 90s.
Supa!