OK for all those who found the poll article ridiculously complicated, thankfully the answer is not.  The wraps should tighten the twists under the serving thread, it's that simple. The photo's below will help explain this using the article reference points. I've loosened the tension on my string to illustrate the point. In actuality when serving on a real tight string you should not even notice the string twists changing. In fact if you see the twists changing then you may want to tighten the string or loosen the serving thread tension.

Option (B1) Northbound Counter clockwise tightens the twists as the thread roles over it. This is correct. You want the threads to remain twisted under the serving thread. (Note: the side away from the serving thread is less twisted while the area where the thread is going over it is more twisted)

Option (B2) When traveling southbound your bobbin will travel in a clockwise rotation this too tightens the twist under the thread.

 

Strings served opposite from the above example will tend to have greater peep movement and the serving thread will be more prone to loosening. The incorrectly served string will seem to want to untwist when not under pressure.