This happens on a rare occasion for me. There are two parties to every encounter like this. If it's happening to YOU (read, "one" not you specifically Tim) then maybe the problem isn't other people

I have found that, generally speaking,
if they respect you they won't pull stuff like this.
Then you dont deal with contractors very often. Respect has little to do with it. I am pretty much the final decision maker on all repairs/improvements/etc at our three facilities. The amount of no shows I encounter for just getting people to give me a quote is insane. The amount of contractors I leave an initial call to and never hear a peep from them is also amusing.
We need a new roof. We received a brochure in the mail. I called the number and spoke to a woman about getting an estimate. Within minutes I get a call back from the guy who does the estimates. We schedule a time.He tells me it will take about a half hour and he will bring some samples to show me. Time comes and goes, and I am now to the point where I have to leave for the day. He calls and tells me he is running way behind had a huge repair issue 45 minutes away, blah blah. He says he is still coming in though and will be there in 15 minutes. I tell him I wont be able to wait, but my maintenance guy is here and he can show you which building needs a new roof and he can get you a ladder if you need to get up there. Told him he could show him the samples and I trust my guys opinion and that he could then send me the quote.
3 weeks later he stops by my office mid-day unannounced and I assume he is just dropping off the quote. Nope. He never came that evening. He is now doing work right up the street and wanted to now take a look at it. Told him no thanks.