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.
The OP never stated what position was being applied for, but either way the employer has the right, IMO to set the rules of what's acceptable for his company.
If the prospective employee doesn't want to shave his goatee, then he is probably in the wrong place for him anyway, and will never be happy.
