User testing at a cafe

So I am sitting at cafe Roma in San Francisco with my IPad product manager, and one of our IOS developers from Hotwire. We are scoping out people to test our New app we created for Hotwire.com. I met a nice lady in line when I was buying a muffin, she is down for testing but wants to eat her breakfast first,(no worries). Cafe testing has it's advantages and disadvantages, the cool part is meeting the users and watching random people use a product I created, it's very fun to watch. The main down fall is qualifying potential users to test on, if you can find your target audience your lucky, but it's just nice to get the product out and get people using it. (20mins later) So we tested two people and they gave us some great feedback, the only main concerns people had was the small details. These small details a not priority for testing unless they are attached to a heavily used framework, if the feature is a stand alone don't focus to heavy on it for prototyping. Give yourself goals for each listening lab, example " lets test the sign up flow" or " let's test the CTA flows", by doing this you will have a focused user testing for frameworks you feel need validation. Don't be shy get out and test your designs any way you can, you will have a way better user experience at the end of the day.