I've never employed a private investigator and I hope I never need to employ one.
I've never had any experience with them but time ago, I had a friend that was a private investigator. She explained to me, how hart is that job. She always said that sometimes is a boring job because you have to wait a lot of hours until the person you are looking for, appears. And the next day, maybe became and exciting and also a little bit dangerous day. Also, she related me some adventures with her job and her cases. Anyway, I wouldn't like to do this job, I don't like this kind of job, too much dangerous some times, too much boring another days and too much exciting.
I haven't had any strange or interesting job due to my profession.