You will not be blacklisted if you drop out of a PhD, but you will have three other obstacles to starting another one. Firstly most potential new supervisors would want to see a reference from your old supervisor, who may not understand your reasons for leaving. Secondly you may not be eligible to receive another studentship from your particular grant awarding body. Thirdly, your track record makes you look like a risk. Don't be tempted into thinking you will be able to lie about dropping out, academic research can be a very small world and you may well be found out.
Whilst very few would condemn somebody for giving up a PhD which wasn't working out for some reason or other, starting one you don't think you'll enjoy in the beginning would be foolhardy. You should really sort out in your mind now whether you want this studentship or not. A PhD studentship isn't just valued by students, academics spend a lot of time applying for them and stake their reputations on the progress of the students they appoint. High drop out rates reflect badly on supervisors and their departments and can affect their future funding.