My top surprise? It's not uncommon to see people using MySQL with ISAM tables as a serious data store, and then half-implementing ACID properties in the application's GUI layer.
("Why would you want to put data constraints in the database? The data has already been validated by client side javascript, making the database enforce foreign keys too would just slow it down...")
("Why would you want to put data constraints in the database? The data has already been validated by client side javascript, making the database enforce foreign keys too would just slow it down...")