http://en.wikipedia.org/wiki/Black_Wednesday
http://en.wikipedia.org/wiki/Criticism_of_Comcast
It's only unprofessional if you're bad at it.
I get what you're saying, and I agree absolutely that it is a morally reprehensible thing to lie, cheat, or take the short-term approach to long-term problems. At the same time, you have to realize that anthropomorphizing companies is wrong. They are entities created to obtain profits, and any other reasoning about them is just going to cause you grief and distress. Accept that the system is made to generate non-corporeal profit-seeking amoral sociopaths, and move the fuck on.
No. It's a fake logic often used to excuse of kind of crooked behavior. This doesn't fly. Crooks are crooks, whether they are a company or not. Companies have those who drive them. If those people at the head can't control their own companies not to be crooks - too bad for them, they bear the responsibility.
No, that's a weird attitude (i.e. I'll create a mess today, next person will clean it tomorrow). One has to be responsible for the mess, and actually preventing it to begin with. What you described is exactly the lack of professionalism.