I'm not a parent, but in my personal experience with my 9 nieces and nephews, the more attention you call to it, the more they'll notice it. Age dependent, of course, but I just remember my sister fast forwording through something she had DVR'd that she didn't want her daughter to see (6 or 7 at the time?) and ALL Kira did the rest of the night was ask "Mommy what was that? Why did you forward through it?" And NO explanation was good enough cuz now she wanted to SEE it for herself. Not even "just commercials, dear" would do it. Now had she just left it alone, she probably wouldn't have even looked up from her barbie.
JMHO, of course, from loads of babysitting adventures.. but the same thing seems to happen if you clasp your ears over a kid's head so they don't ear something.