A lot of you would hate to come and buy fish from me then!
The vast majority of my customers on the weekend are actually regulars whose tank setup and knowledge base I already know, it is only new fishkeepers or experienced fishkeepers new to my shop who get quizzed. It is usually very obvious from the things these new people say or are looking at that gives away whether they are in the know or not.
I dont lord it around acting like it's fun to refuse people a sale, I just make it clear to every customer that I get paid the same at the end of everyday whether I sell anything or not, so all that matters to me personally is the wellfare of the animals I care for.
I have been working in the aquatics and reptile trade for 6 and a half years now and I can honestly say that in all that time, the only people who have even acted slightly offended about my asking them some basic questions, were people who already knew that they didnt have the means to care for their intended purchase but didnt care anyway.
Seasoned Malawi cichlid keepers that I just havent had the pleasure of selling to before only chuckle at the implications when I check that they do have a cichlid only tank, they dont huff and puff and take their business elsewhere because I implied that they might be one of those idiots with a tankful of neons who wants to buy a yellow lab.
If you visit UK forums, one thing you will read most when people are discussing their LFS's is that if a shop assistant who has never even seen you before does not even query the three basics, what volume tank do you have, what stock is in it and how long has it been running, then you should probably not buy anything there that day as it does not bode well.
I guess it's just a cultural difference really that we'll have to agree to disagree on