Being in the low 30's I wouldn't say uncomfortable, but we don't get much from it either.
Most of the 50+'s we see at the clubs are not in great shape male or female and its not much of a turn on for us. I know its not politically correct on swingers boards to mention that age/looks is a turn off, but its true for us. We don't want them kicked out of the club or anything like that, but its just not a turn on.
We don't do much at clubs other then socialize, but I think it would be odd being watched by someone our parents age. Again, its our problem, not theirs, but its just not 'sexy' to us.