I knew a guy a few years back who had his CFI initial and kept it current, but never taught a lesson and he would refuse all students. He had an RV-7 in his garage at home that was involved in a 50-year assembly program, which was of course his excuse for not having enough time. Those of us who actually taught about town would joke about him and say "we're not as good looking as our Hollywood CFI! He flies an RV!". He made us angry perhaps but at least he was fairly honest what kind of pilot he was.