Like his character Leon on HBO’s Emmy-winning sitcom “Curb Your Enthusiasm,” JB Smoove is equal parts persuasive and persistent. “If I had a wrench big enough to get those lug nuts off the Brooklyn Bridge and detach it from Manhattan, I could sell that damn thing,” Smoove said via phone last week, in advance of his March 23-25 shows at The Denver Improv in Stapleton. That assertion’s rooted in truth. The 52-year-old actor and comic was last month profiled in Ad Week for his ability to connect with consumers, being an in-demand pitchman for Bic Men’s Razors, the Jerry Angelo collection, Audi, Crown Royal, Amazon, the Call of Duty video game series and Nike, among other national campaigns. “It’s about being direct,” said Smoove, a veteran stand-up who formerly wrote for “Saturday Night Live.” “When you’re a real person and it comes across that way, it’s more believable.