Someone once told me that patrons who boast of being big tippers (ie "demonstrate their opinion that they value what is being done for them") are the worst tippers in the world.
I've worked tables, and nothing was worse than doing your job and being stiffed for a gratuity afterward. Kinda makes one sour pretty quickly and you only do the minimum and hope for the best - and feel kind of bad afterward when you DO the minimum and they then hit you pretty well.
One day a couple tipped me in advance and I made sure I paid them a bit of extra attention while they were there. I mentioned, at the end of their meal, that what they did was pretty unusual and they asked me what my thoughts were when they tipped me and then explained what I did in my first posting. It felt good, and was a bit humbling, to be trusted to do what was right for what I received; rather than performing a service and hoping I didn't get stiffed.
I've since tried to do the same when I'm in a 'tipping situation', have only been disappointed once, and have hopefully spread the practice - not ONE 'tippee' has initally failed to ask why I'm doing it, and I've told them what that couple told me.