If it's a nice clean ferment, it usually isn't too bad. I'd often have 50 or 60 gallons in various stages of fermentation in various sizes of carboys in a corner of my kitchen and the only time I could smell it in the kitchen was when I had something open (racking, etc). Now that I'm brewing in the basement where there's a lot less airflow, I smell a particularly active fermentation for about a week, and I almost stunk my husband out of the basement for an hour when I racked my stinky sulphurous pumpkin mead, but when bottling a finished wine, there's not much smell to it, no complaints from hubby. Bigger batches produce more gas so if there's a smell it will be stronger the bigger the batch is, but usually even if it is a bit whiffy, it'll only be that way for a week or two. I find the strongest-smelling activity is removing the fruit bag from primary bucket and subsequent transfer to the compost bin, but I rather like the smell of fermented fruit, so long as it's not gone stinky like that dratted pumpkin batch or vomit-y like one recent crabapple batch!