agreed sheepy1209, some people try, and the slated for it.
I was mystery shopped when i worked in a PC shop by one of the magazines. There main headlines from the past 3 months had been about pressure selling in shops.
There criticism of my pitch "didnt talk about printers" My question to them during the pitch was "Do you need a new printer" they replied "no, we just bought one"
so as you said, no matter how hard you try, someone will always find fault.
I have personally never found a fault with halfords, or for that fact a bike my GF bought from argos.
They have all been reasonably made (i mean what can u expect for £80) , good advice and good service. Okay id admit, they didnt have what i wanted most the time, or what i was talking about (was after a presta valve extender) but polite, and honest "never heard of it, we dont sell it. Sorry try XYZ...."
I went into my LBS looking for some Shimano Pedals and got "why would you want them, they are crap, we only sell good pedals aka look, if you dont want them, i dont know "lol" go to halfords" at which point he picked his phone back up and carried on talking.