I haven't been to a con or a public outing yet to have a malfunction, but being very picky about smells and the care of my suit, I can report one thing.
Just earlier this morning I was playing around in my WIP. I'm building it still, but I'm so excited so I fooled around in my half suit a bit. I hadn't put on deodorant for the day. I did take a shower, but no deodorant. Big mistake. I'm getting hot, right? Oh shoot! Better call it a night! Buuuut, I can't get the suit off because I have fuzzy nubs for fingers and the zipper is a hidden one buried under 3 inch fur. Fuuuun. All the while, I'm sweating more profusely and getting hotter by the second. I know I'm creating a stink inside this thing. I'm one of those people that has to wear clinical protection deodorant and I've cleared out some nice shirts over the years because I ruin the arm pits. I also take medications and when you take meds you will stink more often and worse than the average person who doesn't take medications.
I just recently found a new mix of 60 percent rubbing alcohol and 40 percent water. Greatest discovery, works wonders. I've used it on my stuffed animals i can't wash that had nasty funks to them, my fursuits that I hadn't been taken good care off as far as smells go(Naughty me, I just didn't know how), hats, shoes, clothes I wear more than once to make sure they smell nice for a few more wears. Our laundry arrangement is very pricey and we just don't have the money to do laundry all the dang time. We can't afford it.
Let me tell yah, it works wonders! You betcha I found those stinky trouble spots on my suit when I did get it off and then a light mist of febreeze finished it off and gave it a nice scent once the bacteria that made the smell was dealt with.
But yes, be prepared if you are a sweater. Make sure you shower. Preferably a cold one before you suit at a con so you can warm up with the help of the suit. Carry this mix and febreeze in your bag, spray after each use. Spray down everything every once in a while to prevent a funk build up. If it gets to be that way for a while, it might not completely come out of your suit. You don't want that. I have my first fursuit I built that has a smell, but its not a stinky one, I don't think, but it is a smell and I get self-concious about how I smell when other people hug me. So, just take care of your suits. Nobody likes a stinky fuzz-butt. Not even a real animal that stinks. Nobody wants fake stinking fur either.
Maybe wear a cooling vest or a neck cooler to prevent sweating and overheating that would cause you to smell in the first place, which is what I've done with this suit. She's a hot mommaseeta and I'm not talking about her looks, either.
I spent almost a 100 dollars to make sure this suit lasts an I don't ruin it with smell or stains. I bought a neck cooler with extra cooling packs. I even went to the thrift store and bought a newish lunch box to pack water, cooling packs and then neck cooler packs in while at cons or events to make sure I can stay in character and only break to change out the packs. Also, I don't want to sweat-stain a white fursuit! That's why I don't wear white shirts! They all get thrown away or they hang for years or months without being warn in the closet!
Practice good hygiene! Some more than others, restrictions apply!