Some job titles are very tricky to claim as one's own.
Let's say you're at a social gathering and someone asks what you do. Unless the person with whom you are talking has actually heard of you, or unless you can cite the title of a project that has earned you rent-worthy income within the last six months, don't bother appropriating one of these titles. You may very well be great in the role, but it won't matter. The person will think you're full of shit. And for all intents and purposes, you will be.
Anything I'm missing?