I have to echo what boba said, there is no good reason a professional installer would not have some type of meter. Maybe if he forgot it at his last job, but you can buy a cheap meter at Radio Shack for about $20. Buy 2 and have a spare. I personally use a Birdog meter(about $400), which tells me which sat I am locked onto and has signal meter at least as accurate as the onscreen sat display.
The problem is that there are some not so reputable companies that hire "installers" ( I use that term loosely) that roll in their own cars, usually not licensed or insured and poorly prepared/equipped.
I have heard stories of an installer coming to a job with a ladder duct-taped to his roof, or needing to use the customers ladder and/or drill etc...
IMO a prof. installer should roll in a company vehicle or at least a clean work van/truck and be well equipped, especially with tools as commonly need as a sat. meter.