If the bores are chromed, stored in a warmer, dry environment, and you're not too worried about preserving the guns inside and out really well in the long term (years and decades +) then a little powder residue and some sweaty finger marks oughtn't hurt.
On this board I guess you'll tend to get answers from people whose guns are often quite old or valuable, and don't have chromed bores etc; a little preventative maintenance goes a long way on them.
I do have young children so my time is at a premium too, but none of my guns have chromed bores; some are quite old and have already suffered some rusting. My strongroom gets cold which can allow condensation to form on them, so they all get cleaned after use as a matter of course.
RG
