One "gotcha" for Java is that there are actually 2 types of design patterns. Standard design patterns and J(2)EE design patterns.
An enterprise Java app may include standard design patterns in it, but there's also a set of design patterns that are unique to JEE. This set has changed somewhat over the years (for example, the DTO construct is pretty much obsolete now, thanks to JPA), but Sun was doing a pretty good job of keeping an up-to-date reference on their website.
Customer surveys are for companies who didn't pay proper attention to begin with.