One of my customer has a self-proclaimed DBA which is very convincing in meetings but completely incompetent with a database server. (Well, he's full of shit)
The customer has a small web application, with around 20 concurrent users at peak time. The hardware is good (actually overkill), but the performance is just awful. At peak time, the users must wait over 3 minutes for every "submit" they do in the application, operation which often leads to a timeout. (At some point I heard the lead programmer saying that he found a way to fix the timeout issue... by increasing the maximum timeout - but this is another WTF story).
The whole performance issue is caused by the database server. More specifically, by the automated jobs and maintenance plans designed by the "DBA".
Those plans are pure evil, I'm sure the SQL Server team at Microsoft would cry if they knew what this "DBA" is doing with their product... Transaction logs are truncated and shrinked (not backed up) every hour. Databases are shrinked every 20 minutes. The stored procedures cache (which provides the performance boost of stored procedures) is flushed every hour. Indexes are dropped and re-created twice a day. There are data manipulation jobs that are started every minute, even if they take over four minutes to complete (can you spell deadlocks?). It's just incredible.
We had a meeting and I suggested to remove the bad maintenance plans. Unsurprisingly the "DBA" refused. According to him, even suspending the plans for a few hours to monitor how the server behaves without them was dangerous and could lead to terrible damage to the databases, which would take him a full week offline to fix.
Of course the boss does not want to risk such a long offline period. So the "DBA" keeps playing with his plans, while saying out loud what a good optimizer he is and how he is doing miracles every day keeping everything working with the bad hardware.
The sad thing is that their hardware is already overkill, but they will upgrade soon and shovel a shitload of money on the database server. Evidently there will be no performance gain, and my guess is that the "DBA" will complain that the hardware is still too weak.