I can add few things here.
1- They dont know basic civil engineering.
2- They dont know anything about alignment, verticality.
3- They dont know how to lay tiles, how to do grouting, how to do wall plaster
4- They dont konw how to give proper slope to the floor.
5- They cant fix even Taps/showers/(water fittings) properly.
6- They know how to talk big things.
7- One Bugger Contractor with engineer came to me and told, we will fix all the problems but dont write problems to Yahoo Group.
8- One utter useless fellow is made the site incharge who got no control over his subordinates engineers, for your information his name is Vijayan.
9- They have used poor quality fittings e.g. window door jali, which has broken weels and whose mesh is getting rusted.
10- One good excuse they give is supply is not there if you ask them to replace anything.
This list can grow eternally.