Sniffing rhymes with:
griffing, riffing, spiffing, beefing, bluffing, briefing, chafing, choreographing, coffing, coughing, debriefing, doffing, dwarfing, engulfing, fireproofing, golfing, goofing, griffing, handcuffing, huffing, knifing, laughing, leafing, morphing, offing, photographing, proofing, puffing, rebuffing, riffing, rohlfing, roofing, roughing, ruffing, rustproofing, safing, snuffing, spiffing, spoofing, staffing, strafing, stuffing, surfing, waterproofing
Sniffing sounds like:
sampans, semifinish, signifying, skimping, snapping, sniping, snooping, snubbing, snuffing, succumbing, sunbeam's, swamping, symbion's, symphonic, symphonies, symphony's