DPs were over-used by architecture astronauts. For a while I was encountering Factories nested several levels deep, and everybody was making Singleton objects for things that didn't need to be singletons. Ask ten people what a Visitor was and you'd get ten different answers, and there were a bunch of things named Visitor floating around that you needed to read the code of before using, because they were all traps.
I heard of shops that were forbidding code that couldn't be shoehorned into one of the patterns already enshrined within the Gang-of-Four book (even though the book says repeatedly that it is not an exhaustive collection of patterns).
So DPs are bad because, on average, they tend to be an indicator of bad engineering practices, such as cargo-culting and political games. They can be used for good, but if you are considering a position in a pattern-heavy shop it's probably worthwhile doing research into what their engineering org is like.
I heard of shops that were forbidding code that couldn't be shoehorned into one of the patterns already enshrined within the Gang-of-Four book (even though the book says repeatedly that it is not an exhaustive collection of patterns).
So DPs are bad because, on average, they tend to be an indicator of bad engineering practices, such as cargo-culting and political games. They can be used for good, but if you are considering a position in a pattern-heavy shop it's probably worthwhile doing research into what their engineering org is like.