The cut does appear to need some help. It could also be from the last time the wall was painted. There is no way to really know without being there. I always hate it when the previous painter did not leave a nice line if I am only painting the walls makes it hard to clean it up. From the picture I am not seeing anything that says its a terrible job. Pictures can make things look good that are not though. My advice is to try to make the customer happy if that is possible. Some paints do feel dry on the wall. If they are wanting a smooth feel scuff x feels smooth when it is brushed and rolled. The matte sheen is nice. The eggshell is fairly shinny but it will feel slick. If its not possible to make them happy do the best you can and try to come to a fair resolution on the billing. If not possible I would say move on and make money elsewhere.
The guy who taught me how to paint had a saying. I never lost money on a job I didn't do. Some times its best to not do certain jobs whether that is a customer that is too difficult or a job that is not easy due to amount of prep needed or set up of ladders/lifts some times its best to know when to not take a job. I think over the years one can get pretty good at detecting if a potential customer maybe difficult during the initial estimate but every once in a while one sneaks past the radar.
The guy who taught me how to paint had a saying. I never lost money on a job I didn't do. Some times its best to not do certain jobs whether that is a customer that is too difficult or a job that is not easy due to amount of prep needed or set up of ladders/lifts some times its best to know when to not take a job. I think over the years one can get pretty good at detecting if a potential customer maybe difficult during the initial estimate but every once in a while one sneaks past the radar.