The same field appearing throughout an almost zero normalised database. Renamed something different everytime it appears. Date, StartDate, Current_Date, and sometimes as date and some times as datetime, and sometimes as null, then displaying/sorting records by datatime. Which puts them in a meaningless order.
No meaningful information in the error handlers, so that users think the system has a bug/crashed, and they log a support call each time.
The helpdesk system has more bugs than the system its logging calls on.
Being handed a legacy project, developed over a decade or longer, by too many cooks who couldn't code properly, so no comments, no meaningful names to modules, functions etc, and then expected to fix it when it falls over.
You can do in in access but you shouldn't. But that was 5 yrs ago. No I can't open the database either.
Versioning, they've heard of it. Ditto testing.