There should be a definition of grifter at the top of this thread because many of the responses do not fit the definition. A grifter isn't a celebrity you dislike or someone you think is dishonest or horrible or untalented or whatever.
A grifter is someone who spins you a story and promises to deliver something in return for money and then does not. A swindler, a con artist.
Nigel Farage is not a grifter. He promised to deliver Brexit and he did. That was his whole openly stated objective from the very moment he came into public view. You might not like it and you might think he used dishonest tactics (cos he definitely did) but at no point was he 'grifting'. The SNP on the other hand whose whole purpose is to get independence for Scotland are almost certainly led by grifters (police investigation ongoing).
C-list influencers who get paid by brands for promotion are not grifting - they get paid by click/engagement.
Celebrities you think are talentless are not grifting. Stacey Solomon brought out a book, you bought it, you didn't like it but she did deliver the book. Unlike Jack Monroe. Kim K and sisters are billionaires because they sold products to people who brought them. You might not approve of the product or the profit but nobody who gave money to the Kardashians (or the Beckhams or the Spice Girls or Mrs Hinch) did so without getting something in return.
Grifters: Jack Monroe, Jessica Taylor, Captain Tom's daughter, probably Captain Tom, Russell Brand and the fox killer himself,
Posie/KJK might be a grifter but all I know is that when I've bought a product or gone to an LWS event I've got what I've paid for and I understand it's supporting her work or income - not a 'good cause'. If she said it all went to charity then that's different but afaik I buy a product from her and that's how she makes a living and supports LWS.