In all respect to kotter, for me a Cheap Charlie is still a Cheap Charlie. I am one who does scrimp and save and look for bargains so that when in Thailand I can afford to be considerate in my "tipping". But there are others, who have money, but hate to part with it. Everything must be a bargain and all must be negotiated in order for them to enjoy themselves. I have seen affluent people return to the their table at a restaurant to "retrieve" a forgotten item and then pick up a generous tip left by his dining companions.
Perhaps, rather then refer to an "average" tip of 1000/1500 Baht, it might be better to use the term "norm" as in a normal distribution (the familiar bell curve). One significant deviation from the "norm" would give a range of 660-1340 Baht/short time and 990-2010 Baht/long time. (Yes, I was a physicist). Tipping less then a standard deviation would indicate you are a Scrooge while tipping above makes you a Diamond Jim.
And, of course, nothing posted here will likely change the tipping habits of resident expats or frequent flyers, but maybe for the newbies to Thailand these posts will be of some value or amusement.