JD nailed it. Bottom line is to, #1- Do what you say your going to do, #2- When you say your going to do it, #3 How you said your going to do it. Be sure to get in writeing all the details of what services your going to provide and what your not.
Jeff, when we get some time we'll grab that beer. I try not to spray upwards under the seams and into the weep holes. I spray my wash on and then spray down over the siding. This has worked for me and keeps anything from getting behind the siding. With all the mold issues I think its a good idea to try to keep as much water out from underneath the siding as possable