There are in fact many different strategies that advertisers use to motivate buying behaviour. What you're mostly referring to above is brand awareness or corporate awareness which is designed to supplant the identity of the brand in the subconscious. The idea is simple, when you're at the supermarket shelf with a huge choice, research has proven you're more likely to pick a brand you have a previous association with (ie a subconscious bond albeit unknown to you).
The reason advertisers use the techniques they do ie stupid, humour, colourful, outrageous etc is because they are known methods to enhance memory recall. Memory is improved by anything which makes a big emotional impact. This also explains why Government funded campaigns to reduce deaths from various sources eg drink driving, cancer etc are often "hard hitting" because they want an emotional impact to motivate the behaviour change and have the images stay with you so it keeps motivating the change.
I used to work in TV advertising many years ago and the science behind the methods is fascinating. I recommend reading around the subject as there's plenty of published material and you'll come to realise the quite staggering extent to which our daily lives are influenced by advertisers. It's actually pretty scary when the penny really drops and of course the same strategies are adopted by modern populist politicians and in fact the media in general. Sensationalism sells and persuades. Rather horrible really, every now and then I'm tempted to retreat to a remote Welsh meadow and eat Lentils and don a hemp tank top. But the internet would be so slow....no crisps......cadburys don't deliver out there......
