Anyone ever have a good experience with a tenant/applicant who has a 'go-between'?

[Paul Clements]

Every time I list a place, there are inevitably moms, sisters, etc., who are contacting me 'because [son/sibling/parent etc] is busy' (or sometimes away). I find this a little odd and kind of off-putting. Like you're too busy to take 2 minutes to talk to me? And you're going to live in a place you haven't even seen? I get that they want to scout, but sometimes they seemingly want to complete the whole process for them. A co-signer is fine, and I've had those pan out OK; generally not an ideal sign either, but OK.

I say that's fine if just you come to check it out, but we need to meet the actual tenant at some point 'to make sure they like it' (and to make sure they're OK). After that point either the person never shows, or they delay the process too long and it gets rented to someone else. In at least one case I think the tenant might have been mentally ill/had dementia and the family member didn't want that to be known, which is understandable. 

Is this a red flag for people? It pretty much is for me at this point - has it ever turned out good/bad for you?