Are there, in the canonical Gang of Four list, any design patterns that you often find misused, misunderstood or overused (other than the highly debated Singleton)? In other wor
ALL.
Don't take me wrong here, I find them to be a great base and when understood well very helpful. It takes so much out of you to acquire the design skills to know well when and how to apply them in the code. Actually, that's the overall case for the skills to create clean code.
Its not about not using then, is exactly what you said in the question "think twice before using". Understand well what you are doing and why. If you don't, talk to someone that can coach you on that - besides reading a lot. Beware of the ones that know all the patterns but can't explain you clearly the what/why of any of them - specially of the one in question.