The term "snitch" never applies to one's client who -for whatever reasons- decided to cooperate. It is reserved for those who are shafting your client by helping the government. We go to battle against them presuming them to be liars, and we certainly try to show juries they are prevaricators of the worst kind and for the worst motives.
But I have learned that sometimes -unusual, but it happens- some of these fellows can be of great assistance to your client. For example, I recently had a case in which every government witness who had stated anything about my client seemed to involve him as the owner of marihuana and cocaine drug points in a public housing project. My client always denied that he dealt with any cocaine. They also involved him in a few murders, and the government intended to present that evidence as well. My client denied ever participating in any murders.
Some months back, one of my client's co-defendants --who knew him far better than any of the other witnesses-- decided to cooperate (see? . . . no "snitching" here) with the government. We had been trying to reach a plea agreement for some time based solely on my client's marihuana distribution and leaving out any cocaine or murders. This had been impossible until that co-defendant started cooperating. He was the supplier of marihuana for my client and had participated in the very murders in which others had stated my client had participated. He has clarified that my client had nothing to do with the murders, and that my client sold only marihuana, and the government considers him a much more knowledgeable witness than the others, as least as regards my client.
So you can see that this is one case of a snitch actually coming to one's assistance by simply being truthful.