This may sound noobish, but I have never worked in service industry, so this was a new concept (me being service provider and interacting with "customers") for me.
I recently I had a gig for fun where I was a bartender at big private company event. I was responsible for pouring straight drinks and beer (me being non bartender) and other guys were doing cocktails (as they were real bartenders).
A chick came to my station and tried ordering cocktail, I explained that I only pour straight drinks/beer and sent her to other guys. She said - you do not know what you are losing.
She was not giving any IOIs (like not even smiling) so I was wondering, was it:
a) she just did not like being "rejected" for service and said that in not "dating" way, eg. she was not interested in me as a potential partner.
b) this was a clear indicator that she subconsciously meant she wanted to talk to me etc
I am intermediate or even advanced guy in reading situations (if someone told me that phrase in real life situations I would of course assume attraction), but since I had no experience in service industry, maybe this was not attraction related issue, but just "you losing me as a customer" thing...