I don't read 'testimonials' provided by somebody trying to promote me some flaky deal on some flaky product, I don't accept letters of reference or advice on resumes or job purposes (nor, even, the applicants who provide them) until the advice is from somebody I know (and even then I'm going to name them and question it), and I don't 'play fair' when it comes to reference checks: I am going to ask anybody I deem likely to know. I am a useless serious believer in running a background check on everybody you hire who has entry to guestroom keys, period.