The only way I've been able to make coughs and sniffles less distracting is to cut them out of the audio track. You end up with short audio drop outs, but that may be less annoying than a sniffle. Your ear glosses over and ignores drop outs more than an annoying noise. You then blame the audio defects on a bad mic
. I've tried a number of sophisticated filters but none were as satisfactory as just cutting the audio.
I use FCP and there are several methods for marking the in/out points on the audio and then dragging the level down. I use a slow brute force method, but I think I read about a quick/easy way to mark a segment and drop/cut the audio level.
I could try to find the tip if you are at all interested.
From the lesson learned the hard way, I now use a directional mic located much further away from my face and have not had to deal with post editing sniffles. Too late for that now