I like watching for patterns, and when I’m bored, I look for patterns just to keep myself awake. That’s how I came to notice the use of colour in an ad for a bank (I think) that starts and ends with a young girl holding an old-fashioned alarm clock beside her face. The ad is calling for planning (financial, I assume) but what I noticed after I’d seen it again and again, was that in every scene the woman was at a different life stage, and in every scene she wore a blue piece of clothing. Not the same blue, but always blue. Incidentally, the company logo was in blue.
Having noticed that, I watched an ad for a bank that uses orange as its colour. It was even more subtle, but every scene had orange touches in it.
So now I’m able to amuse myself when I see the same ads again and again. Currently I’m researching their subtle use of colour to point to their logos. And looking for other patterns.