I have multible crews and I work as well. We all have uniforms (uniform service). I totally agree with GMLC. We have both upscale (full service) and not so upscale accounts (mowing only). I would never ever never ever show to a upscale (full service estimate) with out being cleaned up best I can. However, I will go do a quick estimate for a mowing only customer as I am.
I also agree with yardguy, do what ever suits you. I too work mostly off referrals and as for me I will always put my best foot forward with the upscale full service customer. Because I believe that your image represents the quality of your work. When I meet them I want them to see someone who looks and acts professional. That's not an absolute fact, but its common perception with the the higher dollar accounts that I service. We routinely get comments stating our teams look and act so professional.