I try to keep a spray bottle of star-san solution handy for just such things. It's even more important for sankey kegs IMO, since the keg valve tends to collect moisture and dust/debris. Some smaller microbreweries around here have even tried getting the bar employees that carry their beer to do this when swapping kegs. If you keep your kegerator/keezer at or below 36F it's much less important, since most of the nasties that can infect your lines aren't active that cold.
I'm trying to find some porn filmed by a dog wearing a GoPro. - SharonaZamboni