It's someone's job to pick music for TV idents, advertisements, trailers and in the middle of TV programmes when they're showing pictures but have no accompanying voice-over.

Music is used constantly to lend atmosphere to anything which is broadcast.

This is a job which I would love to have, though unfortunately it is just a small part of bigger job, as otherwise it would be too good to be true.
Actually the job is done easily by entering a key word into a computer which will give you a selection of relevant tracks, so a knowledge of music isn't even necessary.
In the past there have been flavour of the month tracks which have such popularity and generic appeal that they have been over-used, and there are also old classics, such as "Summertime" which has been used to lend a mood to almost every holiday/travel programme to denote a relaxing destination.

However, I have been deeply disturbed recently by the relentless use of Moby everywhere. Yes, I know that it's the only album ever to have every single track licenced for commercial use, but I think the people who choose incidental music must by now have forgotten what they did before Moby came along.

I loved that album, but

'nuff Moby already!