"You know, testers in a team can be a liability for the quality of your product.
How can you even say that? We hire testers to improve quality! Besides, aren't you a tester?
Yes, and because I know of this risk I can do a better job.
Alright, I'm intrigued... how?
There are three main perspectives to keep in mind when talking about quality: communication, ways of working and techniques. If you are being deliberate about them you can mitigate the risk that the tester poses. I've got lots examples of techniques for each perspective, let me show you a few.
By the way, did you know programmers can test their own code?
Now you're just being silly..."