My GF's parents have had a patio installed in a way that I believe is of poor quality. They have just called same ontractor back to do another patio and I feel they are making a huge mistake. What are standard signs of a poorly installed patio? Here are a few things I noticed that were wrong. Grass is growing up between the pavers all over the place. Around the pool, the stones in the corners have cut marks on them. He used very tiny chucnks of pavers in many places that are loose. A few bricks here and there are sunk in a little bit. Can someone shed some light on this? I could post some pics if needed.

I'm planning to install a paver patio and have a question about drainage. The patio will be 24' long (against the house) and go 20' out from the house. I plan to do a 2' high sitting wall along the entire patio length opposite the house. I will be using 6" of base material and 1" sand under the pavers. The backyard currently slopes slightly away from the house to about where the sitting wall will be, then it goes uphill rather quickly from there (essentially forming a swale at the proposed location of the sitting wall). My question is, since the patio will slope away from the house toward the sitting wall, do I need to anything special for drainage where the patio and sitting wall meet? I already plan on burying a drain pipe on the other side of the retaining wall to move the water coming down off the hill, but what happens to the water on the patio which runs toward the wall? I don't want to end up with puddles up against the sitting wall! Thanks!