You must feel comfortable and believe they will approach your request with the utmost effort. Don't be afraid to ask any questions before you hire a private investigator. It all depends on the type of case assignment, area of the country or world, and the firm accomplishing the work. Accomplishing surveillance is something we do all the time. People should understand this simple issue.
Surveillance is often dangerous and unpredictable.
To be accomplished correctly requires training and experience. If knowing someone's activity is important, hire a professional. If you live near them visit the local County courthouse and conduct a review of available records. It has been our experience over the years that if the situation is important enough to affect your personal, business, or financial future, strong consideration should be given to a background check. In today's world we often don't trust our instincts enough.