I always wear my regular clothes. The touring bike has full coverage fenders so no issue even on the dirt roads. I also use the dry lube wax type stuff on my chain to that's not too much of a problem and just pace myself and use antiperspirant to avoid sweat in the warmer months.

The Dutch solution to drivetrains is also a nice one, lot of the bikes sold in Netherlands are of fully enclosed drivetrain and with geared hubs it's not too much of an issue anymore. Not my style personally but a pretty good implementation none-the-less.