For the ethical investor (which is of course a spectrum and not binary, therefore arguable), coca cola poses several issues.
Chiefly, their seemingly abhorrent abuse of water resources (namely aquifer depletion) in third world nations has a profoundly detrimental effect on local inhabitants. India is a very good example.
I will not buy coca cola products for this reason. I certainly will not buy their stock.
It's a moral judgement for me.