What are the chances that people doing a total renovation don't spot an hidden camera?
.
.
.
Oh, well... Surely higher than the probabilities that a
hidden camera has
a fucking blinking LED to indicate it's operating...
And even "more higher" than the probabilities that Derek had to
sleep there for half a semester before noticing a
fucking blinking red LED in a dark room... 

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Yeah... With such a level of
perfectionism in the plot, Bazsa4 is right:
...if we interpret "to make sense" in a brooooad AVN-logic sense, of course.
Like when we say that 1+1=3
for large values of 1.