> Are you assuming these folks are ... or customers are sharing via word of mouth?

Seems fair to me (interjecting: not the parent poster). I rent, too, but have heard countless conversations along these lines among Proper Adults.

Often grown-up #1 complaining about their latest project and grown-up #2 offering someone that served them well in the past. Point being, bad experiences are both so common and costly... that those who are good tend to stand out and stay busy. IME, those listings or the phone book are most suitable when you don't have a relationship to leverage (effectively rolling the dice).