What exactly is considered to be 'Milking'?

[IamAwsome]

I would consider milking to be when a publisher releases several sequels to a franchise, and that franchise either
A. Drops in quality (Sonic before Colors, Mario Party, Twisted Metal in the late 90's)

or

B. Doesn't add much to each new installment (EVERY major Activision franchise excluding Blizzard ones)

I wouldn't consider Mario, to be milked because the quality is there, and the gameplay is different from spinoff to spinoff (Mario Kart, Paper Mario, Mario vs DK, Sports games).

Halo is a franchise that could go both ways because it gets so many installments, and because Microsoft relies on Halo for the holidays almost each year, but each new installment is good, and adds a decent amount of content.