Now this is a resume: dapper king of Miami soul, groove-master songwriter for the likes of Sam & Dave, rap trailblazer, and the novelty-act progenitor of both 2 Live Crew and Weird Al Yankovic. For the past 40 years, R&B legend Clarence Reid has been better known as Blowfly, a potty-mouthed, purple-hooded alter ego responsible for such crass classic parodies as “Hole Man,” “Shitting on the Dock of the Bay,” and “Should I Fuck This Big Fat Ho?” This affectionate if occasionally leering documentary reveals Reid to be an indefatigable performer, paranoid loner, and limping late-sexagenarian who’s still the filthiest boy in the room. Having sold his lucrative catalog for a paltry sum to pay debts, Reid teams with road-hog percussionist Tom Bowker to wring a meager living out of the Blowfly legacy, which sends them from sparsely attended saloon sets worthy of Spinal Tap to a sold-out festival show in Dresden where our caped offender dodges projectile trash. Although his subject is never less than captivating, Jonathan Furmanski’s film is frustratingly unfocused, a scattershot collection of candid footage and biographical information that never coalesces into a legible portrait. Thankfully, Blowfly’s world is as weird as promised, a discordant mélange of hairnets, hissy fits, ornate cock talk, and cockamamie fears of the feminine sex.