I weigh most of my stuff at home just because I trust most of my dealers. But every once in a while when I get stuff from an unknown hook, i'll weigh it there. It helps to have a friend with you or something so that you have the upper hand in case they get all butthurt or pissy if you catch them ripping you.

The biggest problem is when they try to count the bag as part of the weight "the bag hardly weighs anything" they say, when its really like 2g... And I love it when they leave it all connected to like a fat stem and are like "that stem doesn't weigh anything" and it turns out the stem itself is like a gram...