I have at least one customer that's nitpicky to the point of insanity during every one of my shifts at a famous coffee chain that likes alliteration.
I am completely fine with going out of my way to make a drink special for someone. For example: someone that likes me to put their caramel/mocha shots in after the espresso or someone who wants me to do something out of order because they think it mixes it better, etc. However, when someone TELLS me how to do my job (that I've been doing going on 4 years now), well, that's where I draw the line.
I've told customers that if they're going to be that picky (especially if it's during a rush) that they need to get their own machines and make it at home. I'm trained to make the drinks well, and it's my job.
I'm not trained to have someone tell me how to make drinks/food items that I've been making for years now.
This whole concept infuriates me.
I am so glad that I'm an iced tea drinker. Really, all I do is put in Splenda and I'm done. No lemon or anything. =]