Are you trying to design a logo for your business or organization. Here are some common mistakes to avoid:
The Nazi symbols like stylized swastikas do not generally work well. Some people are ultra-sensitive to them, and the skinhead market segment is small and doesn't have a lot of money.
While subliminal dirty pictures are quite enjoyable to those who enjoy the embarrassment of others and things like fart jokes, these logos won't get printed even if you sponsor events like a run for cancer or the White House Dinner.
Kids aren't treated as resilient commodities like they were in the 1950's and 1960's, so its best not to traumatize Momma's lil darlings.
Again, these genitalia and sperm logos appeal to a certain sector of the demographic, but generally the mirth that they provide doesn't translate into respect.