Unless they start asking to see DVC member cards, I can't see how they can determine a member from someone else.
I booked 4 nights at OKW for a friend and his room card looked the same as mine. It said "DVC member" on it. I was not with him on that trip. so if he chose to pool hop, I don't see how they would of determined he did not belong.
We were asked to show our DVC member cards at SB prior to BCV being built. We pool hop a lot. Probably more than most members. In fact, we've made whole days all about pool hopping
Most of the time we call first, especially to some of the deluxe resorts. We don't normally travel during peak times and we forget, but never stay at any one place too long.