I can understand occasionally working out of a coffee shop. But who does this all the time and remains productive? And is it really fair to the coffee shop?
As for being fair to the coffee shop, it's just become a way of life recently. If you don't want people working from your shop, don't offer wifi. The shop I'd been going to for over a year recently stopped offering wifi so I started going to a more worker friendly shop.
I do, and I'm pretty productive. I love the white noise of people around me, and its stimulating enough having different people come in and out, without being overwhelming.
I buy at least a cup of coffee and a snack for every 3-4 hours I spend in there. Most of the local coffee shops I work at know me by name and usually can guess what I'm ordering before I even say anything, so I assume it doesn't bother them :D
Funny example. Last week the person next to me started a conversation about emacs. I mentioned I worked for WordPress.com, and then it turned out that two of my colleagues from Automattic (one who I hadn't met) were working just two tables over. This is in Boulder, I was pretty floored and excited to actually be seeing folks I work with in person.