This is a simple thing really, that no one in low elo really knows.

So, after you hear a tap, you wait for a whole 2 seconds. This applies generally in 1v1 scenario, but in other situations also you can apply this logic.

LOGIC: so if it takes about 3.5 seconds to half the spike, if you peek at 2 seconds, then if they were faking, you did not really fall for it. If they stuck, you get free kill, and it is not even halved yet.