A clone taken from a beat up, stressed out, ragged mother may be difficult to get going. It was stressed and deprived before cutting, the cut doesn't have much energy to root and grow. The end result may be less than desirable as the resulting crop has a hard time getting a foothold. Not going to have a good time cloning, or getting a crop going from this plant, even if it's brand new, grown from seed and never before cloned.
A clone taken from a healthy, vigorous mother, will root quickly, begin taking in nutrients, and thrive. The end result is much better, and the overall grow much easier for the farmer. Cloning will be easy, and a new crop taken from this plant will hit the ground running, even if the mother is 10 years old and had cuts taken 100 times.
What is relevant, is the condition of the plant you're taking clones from, not how many clones have been taken from it.
A clone of a clone of a clone of a clone of a clone of a clone... is still a "clone". Degradation of the plant in question, as a result of cloning is pure myth. When you think of cloning a cannabis plant, you think of "making a copy". You're not actually making a copy. One plant is not going into some botanical xerox machine, having it's genetic code read, and a new plant constructed from all new materials according to that code. This would allow for errors and omissions, and degrading resolution of the genetic code with each copy, just like a photocopy of a fax of a sketch of another photocopy. The image gets less clear each time. While our brains might perceive it this way, this is just not whats happening.
What IS happening when you clone your plant? You're simply taking a piece of that plant. It's the same plant. Not a copy. Think of the lizard that grows his tale back after he loses it. Now imagine that the tail he lost, grew a new lizard. You could clone a plant 100 times, but that 100th plant is still just a piece of the original, not a copy in any way.
Clone a healthy plant, get a healthy clone. Clone a pissed off plant, get a pissed of clone. Make mom happy before cutting, period.