Here are some interesting thoughts on the topic by A.W. Tillinghast from the book, "The Course Beautiful" . . .
" . . .The best players will tell you that they like to play to a green that stands well up in the back. This is not a new observervation, and yet the country is fairly cluttered with symmetrical "pancakey" greens, which slope away from the line of play in a most brazen manner. They are utterly worthless and heartily cursed by every true golfer, and yet, strange to say, a great many similar putting greens are being built today. Such ignorance is inexcusable.
Naturally, those greens which are to be gained by lofted shots from iron clubs should slope more into shots than those which, under ordinary conditions, are reached by the finish of balls running from wood. The irons are designed to create underspin or "stop," and unless the green faces properly this spin cannot become effective. No matter how crisply played by master hands, a ball falling upon a receding green can get no bite. . ."
There are a number of other "interesting" opinions offered in chapter 22, Featuring Putting Greens, in The Course Beautiful. Here is a quick example:
" . . .What could be more unfair than the introduction of pronounced undulations in a green upon which the player is supposed to pitch? It is obvious that two balls, each receiving the same same amount of under-cut, might strike within a foot of each other, one on the ascending slope and the other just beyond, where the ground falls away. Every golfer knows the action of these two balls and appreciates how much the element of luck has figured. Consequently undulations should be reserved for greens other than those upon which we are to pitch . . ."
Pretty interesting, huh?
-Ted