Most people will not find you creepy because they are not attracted to you. Most people will not find it creepy if you flirt and they are not attracted. They will find it creepy if they don't respond to the flirting and you continue to do so. They will also find it creepy if you start from a position that doesn't leave them an option to politely disengage from flirtation (e.g. starting with "want to fuck?" is creepy because it gives no chance to the other person to participate in what should be a mutual escalation of attraction - that you have already decided their level of comfort with the notion is a personal boundary violation).