It was raining today so I decided to check out if my Marmot Precip is still waterproof or not? I wore my synthetic jacket underneath. I was going to run a circuit but then decided to walk it, just about 3 miles. By the time I was back at the bus stop, I felt a bit wet in a couple of places, along my arms and across my chest area. I took off my Precip on the bus, the outside of the jacket, of course, was wet but there were a couple of damp patches showing on both of my synthetic jacket sleeves. This is where I always have a problem, how do I tell the difference between a jacket that leaks from the outside to the inside to make my sleeves wet, or is it just damp caused by the build-up of moisture inside of the jacket, caused by the act of perspiring? Has anyone worked out how to recognise one from the other?