I've said to more than a few, "I've been printing since 1972, and you never have. Explain to me how to do what you want." Silence, followed by a bit of stuttering. "Well, my friend said..." to which we say, "So why are you here if your friend can do it?" More silence and stuttering. I very politely tell them that I run my shop, and no one tells me how to do it. If they don't like my work or my price, or want me to do shoddy work to meet their price, then they need to go elsewhere, it's a big world.
Steve