A vampire professor will suck you dry. They will rob you of your life essences. Exactly which essence they will remove might vary with professor. Some will suck away all your time. Such a professor will notice when you arrive and leave, but not necessarily whether you are productive or spend your day reading my blog. You may work all night in the lab, then come in at 10 instead of 8 and be criticized. The only way to please this kind of vampire is to be in the lab all the time. Tricks like opening your door whether you are there or not may sometimes help. Weekend time at the lab is mandatory, but must overlap with when the vampire comes in.
Another kind of vampire professor will claim all of your ideas, rather than nurture them. I once read a web page of a professor who said that all ideas anyone in his lab had while in his lab were to be considered his (the professor’s) ideas. Furthermore, no idea had in his lab could be pursued after leaving the lab. Ideas should be shared, coddled, elaborated, enhanced, celebrated, so the best ones can be pursued. Vampire professors want your ideas, but what they want to do with them is not always clear.
Perhaps the worst kind of vampire professor wants your soul. They want your life to center on your work in the lab and your relationship with the vampire. They do not want you to have outside interests, or to develop outside scientific interests or skills. They want your very blood.
Is it worth joining the lab of a really famous professor doing super cool research who also happens to be a vampire? I say no. Research should be mostly fun. Grad school should be mostly fun. But above all, the lab community should be nurturing to you, not to the professor alone.
Garlic won’t help avoid vampire professors. Read their web pages. Talk to their current graduate students. There will be plenty of clues of a vampire professor. They are insecure and you can smell it.