Wearing a uniform or not wearing a uniform should do not denote the quality of service that you should expect 

We and myself personally love to see a service person come in a uniform, present me with a proper business card and drive a truck that is lettered for their company.

It just shows that little bit more of a level of professionalism but... the proof is in the pudding.

You can put lipstick on a pig but I want to see good workmanship no matter how you look ..but agsin, Iwould prefer a nice clean uniform. 

It shows their company cares what their people look like.