At places like Golden Buffet, 10% to me is adequate. I usually tip 20% at regular restaurants due to my lack of math skills (especially after a few beers LOL)! It's easier for me to work in units of 10, and 10% is not acceptable in my book. Servers usually work very hard for sub-standard wages and rely on tips for their income.
That being said - on December 30th we took some dear friends to the Ale House near FtW (we really talked the place up to them) and had a HORRIBLE server. I was embarrassed by our lack of service. In the almost 10 years we've dined at this restaurant - we've always had terrific service. Not this time! Not only did I not leave any tip at all, I asked for the G.M. and complained about our server. I told the G.M. that the meals were outstanding, as usual, but the server was very bad. The G.M. gave us 25% off our meal - which I told him wasn't why I was bringing the server to his attention - but because if he were my employee - I'd want to know what a goof off he was.
There were two booths behind us with 8 very cute girls dining out together, and this guy was all over them & ignoring us. I understand the server's "fawning", but by my reasoning, he probably had this job to make money via tips. He made no money off of us that evening, lost some profit for the restaurant, and may have lost his job because the G.M. told us that he'd had a lot of complaints about this guy, but needed to keep him to get thru the New Year's weekend.
My assessment of servers is this: Servers are the host to the guest and are thereby obligated to make sure all of the guest's needs are met. A guest can't get up and help themselves to another drink, nor can they go to the kitchen to find out what the hold-up is. A guest is at the mercy of a server. So - if a server doesn't have that basic concept going into the job - they need to find another job they're better suited for.