In my experience, money calls into question the sincerity and authenticity of both the person paying, and the person being paid. Authenticity being "are they being themselves?", and sincerity being "do they want you to know themselves?" and vica versa.
Is a person being friendly because they like me or because they are counting the dollar signs in their head? Do they really want to get to know me or are they simply being polite, i.e. applying social lubricant?
I don’t have a single host from my AirBnB stays that I remember fondly, if at all. I have several Couch-surfers who I miss dearly and who message me from time to time on Facebook.
I feel that it’s possible to make real friends with people you start with on a “business level”, but until that “business” gets removed, the relationship is just a thin veneer over what is essentially a transaction.