Comment by JoshTriplett

Generally speaking, I think the point of statements like this is to shoot down the trite and thought-free cliche "if you have nothing to hide". And the point is rarely to convince the person you're speaking to, it's usually to get people who might otherwise be swayed by hearing the trite and thought-free cliche to think for a moment.

If you're talking directly to one person and trying to convince them, without an audience, there are likely different tactics that might work, but even then, some of the same approach might help, just couched more politely. "You don't actually mean that; do you want a camera in your bedroom with a direct feed to the police? What do you actually mean, here? What are you trying to solve?"

Option A: "Yes!", which tells you you're probably talking to someone who cares more about not admitting they're wrong than thinking about what they're saying.

Option B: "Well, no, but...", and now you're having a discussion.

Generally speaking, people who say things like "if you have nothing to hide" either (charitably) haven't thought about it very much and are vaguely wanting to be "strict on crime" without thought for the consequences because they can't imagine it affecting them, or (uncharitably) have attitudes about what they consider "shameful" and they really mean "you shouldn't do things that I think you should feel shame about".