I strongly think it is and obv. this lowers the overall quality of this forum as a source for useful information. As soon as a newbie asks a question, sig spammers start crowding the topic with their 99% sensless/false/bs answers. Some (most?) of them didn't even understand the topic!
@Theymos: The problem is not created by the sig spammers, but the system allowing it. There might be a point where Bitcointalk will be rejected by the users, when you can't find the information you are looking for, because it's hidden in a flood of trash.