Servers already understand the process, and the requirements. If they suck at their job - tell their manager, and if it is a corporate restaurant, call their main office.
Actually, probably the better remedy is if they suck at their job, tell the Internet. There are restaurant reviewing sites for that purpose, and their manager or main office isn't likely to do much.
By the same token "servers talk about people who stiff them" might not be much of a deterrent to someone who was sufficiently vengeful (or entitled) to actually stiff them. If their experience was really that bad they might simply not go back to that restaurant again.
Ultimately telling people they will be thought of as a douche if they don't will never increase the consistency of tipping. Some people just don't care about being thought of that way, or are entitled enough not to care if servers think of them that way. Some people don't give a toss that your boss doesn't pay a living wage and view the interaction as what it's theoretically supposed to be, an optional reward for good service. Some people think of themselves as consistent tippers but may just screw up the math, or have a party skip out on the bill, or any number of other things. Direct gratuity is inconsistent by its nature precisely because it can't compensate for variables of personality, interpersonal chemistry and circumstance, which is precisely why a system that relies on it to the near exclusion of anything else (even to the point of treating it as taxable income) is just abusive. And that abuse is ultimately being meted out by the industry, not the customer.
