OK then, I'll just disagree with you.

People are surprisingly easy to offend over email. I know that I've offended some when sober. Sometimes it's because I'm too terse. Sometimes it's because they're reading something between the lines that I didn't mean to say. Sometimes I phrased things poorly. Sometimes I wrote it the email in anger.

Add 2-3 drinks in the mix and I'd probably double the number of offended customers.

Taking customers out for drinks is a completely different situation. It's a lot harder to be misunderstood in face-to-face conversations, not to mention that the customer is drinking along with you.