Clients that send packages and tell you that you should consider the embedded termbases, whereas these even don't contain your target language.
Clients that send packages with big TMs that show to be empty. The size is caused by the efficiency of the database module of the originating CAT tool.
Clients that require you to log in to their PO portal and download a job package, just to see that it's not your cup of coffee.
Okay, let me focus on the bright side of life.