It's nothing you can't fix with a couple of centimetres of electrician's insulating tape ..... if you get a knock on the door after covering up the lens, then you can be sure they were on to you. (Of course, *not* getting a knock doesn't mean they don't know; they might well decide to leave you alone if they do not want to blow their cover. Perhaps they'll just find another way to spy on you. Come to think of it, they might have done that already, hoping that you will block the laptop webcam lens and not expect there to be another hidden camera in your home watching you.)
Anyway, face recognition may not turn out to be such a bad thing in the long run. The abstract mathematics underlying face recognition is basically the same as the abstract mathematics underlying decompilation. If a computer program can be written to recognise a human face, then another program can be written using similar algorithms to take a compiled binary program and produce a piece of Source Code that, when compiled, would give a binary identical to its own input. (Variable and function names might well be lost, but meaningful names could be deduced later from context by a human programmer.)
One other, very interesting point about decompilation is that since in theory a program to perform a given effect can be written in any programming language, the decompiler's output need not even be in the same language as the original program was written. This would enable an alternative use, for translating one programming language to another.
If one person thinks of something, then that's a sign that somebody else could think of it (cf. Joseph Swan vs. Thomas Edison with the light bulb, Alexander Graham Bell vs. Elisha Gray with the telephone and Thomas Edison's phonograph vs. Emil Berliner's gramophone.) So if one team of mathematicians can formulate the necessary equations for recognising a human face, then another team of mathematicians can formulate the necessary equations for decompiling a binary. The maths is exactly the same, just with different meanings for the figures; just as the equation for current flow in a coil when a voltage is applied to it is the same as the equation for the speed of a moving object when a force is applied to it, and note also all those equations where energy = .5 * something * something else squared.
The existence of a decompiler would revolutionise the computing world. All software would effectively become Open Source (it would become possible to take Freedoms One and Three by force, just as it is possible today to take Freedoms Zero and Two by force). Programmers would not be able to disguise shoddy code, and malware could be quickly identified and neutralised. And two or more programmers could work on the same project without even having a programming language in common.