But here's the catch: If you connect the circuit wires to the wrong terminals on an outlet, the outlet will still work but the polarity will be backward. When this happens, a lamp, for example, will have its bulb socket sleeve energized rather than the little tab inside the socket.

Does it matter which wire goes where on a light switch?

With a switch loop yes, it should. The hot wire should come down from the ceiling on the white wire and go back up on the black wire. Just think 'white down, black up'. If you wired it the other way around, hot black down and hot white up, you have a problem.

Can you reverse a light switch?

If you can find the other switch, flip it once and now this switch will be reversed and work the way you expect it. If it is a 3-way switch and you can't find the other end, you can simply remove the switch and replace it right-side up and you're done.