My dryer was not getting the clothes dry in one cycle.  Sometimes not even two.  I clean the dryer vent after each load, but I had never cleaned the vent in the back of the house or considered the entire pipe.  This was in my dryer pipe after 15 years…..

Let my grossness be your warning.  CLEAN YOUR DRYER VENT!  (Sorry for the yelling!)

Here is how: http://www.wikihow.com/Clean-a-Clothes-Dryer-Vent

My dryer works better now!  You might want to try yours.

Kim