I think it all depends on what aspect of the trade you're in.
There's a World of difference in one of those "white-shirted-polished-shoes" guys that does residential service with a yellow pages ad, sends "technicians", and a guy that does tract home, or industrial construction.
Exactly Scott,
I have myself shown up to early morning faults calls with the PoCo with my hair sticking up and been un-shaven.
I've never had any bad comments about my appearance to date, people just want their power back on and everything back to normal again.
Normal daytime calls are a totally different thing though.
Some of the best industrial electricians I know have the most wildly un-kempt hair of the human species, no-one cares though, they are good at what they do and in a factory situation, that is what matters.
