Ahah! Now here's something I know about and an oppty to help!!!!
I have had constant sinus issues since I was a kid...always with the sprays and pills and all kinds of junk...big frustration, nothing *really* works to permanently resolve it except surgery (which I don't want)...so I live with it and try to manage it.
If you are having sinus trouble (as I *always* do) you can feel like you are breathing fine etc but you can still have mucous coating your tongue and olfactory nerves, etc. and you wont notice until after you've lit the cigar and start being disappointed, etc.
Here's what I do, (I do it as a sort of daily ritual along with brushing teeth etc in the morning)
1) try "Neilmed Sinus Rinse" there are a couple others out but this one is relatively inexpensive and easy to find at CVS so you don't have to go hunting...follow instructions either first thing in the morning, or at least 1/2 hour before you want to smoke a cigar. Your sinuses will be clear and most importantly your olfactory will be fully functioning for that awesome bouquet of complex smells and flavors.
2) Gargle with well diluted lemon juice this will literally dissolve mucous, oils etc on your tongue and cleanse the palate to refresh your mouth, then swish with water to get rid of the lemon taste (unless you like lemony tasting cigars!)
*note: at first the sinus rinse process can seem gross and uncomfortable...but once you get over than initial hesitation, it really is a nice personal hygiene thing that actually is comfortable and refreshing once you get the hang of it, especially if you are not feeling well in the first place...PLUS I have noticed doing this on a regular basis absolutely cuts down on the number of times I get a cold or sinus infection, as I followed advice and sometimes put a few drops of iodine in there for anti-bacterial effect.
Hope this helps, as I have suffered a lot but refuse to have my cigars wasted because of my stupid sinus issues
Good luck!