I put as little as humanly possible on my CV to reduce the chance of getting asked about stuff I have pretty much completely forgotten about.

I hate preparing for interviews and don't want to brush on my past. For example, I spent a year writing an LLVM backend for a DSP but I'm pretty sure I couldn't write more than a fizzbuzz in C++ now. Nor do I remember much about LLVM. I don't want to come across an LLVM enthusiast and have him start grilling me on details I have long forgotten.

I try to write just enough to get an interview, anymore information makes you more likely to fail your interview in my book. Plus writing less makes you mysterious ;p.