Cooking generally refers to fermentation at a slightly higher than normal temperature, maybe 8-12 degrees. The two most common ways of achieving this is either by keeping a fire going in the aging barn and elevating the ambient temperature about 10-12 degrees, or by steaming the fermenting leaves. There are pros and cons to both, and I don't think there is really anything wrong with it, it's just another process.
Most tobaccos will cook naturally during fermentation, but cooking can help speed up the process or achieve a certain desirable color. In the end if the consumer likes the result then it's a good thing. If the consumer doesn't like it, then they will let them know.
Yes, some do use dye, and others use a sugary water spray, or a spray of tobacco resins. Again, consumers can decide whether this is a good or bad thing with their spending. So there is no real answer to whether this is a good or bad thing. It's just another process.
