They take everything out and give it a quick glance and sniff. They may open your luggage and check in your tent and sleeping bags. For some people it is thorough...for others it is not thorough at all. I went in early and they were pretty thorough for most people. I can't speak for people going in later in the day.
I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion. I watched moonbeams glitter in the dark near the Tannhauser gate. All those moments will be lost in time... like tears in the rain...
Did you not read Gemini's reply? It depends on the person who is searching you and what time you get searched. No one answer will be accurate, and apparently no answer will satisfy you. If you are worried, crotch whatever you are trying to "sneak" in
Edit: and if whatever you are trying to get in does not fit in your crotch or amongst all car riders' crotches, I would say leave it at home.