I actually quite like adverts in the underground... in London I always look at the posters when on an escalator to see if any shows (musicals/plays) look interesting, and I still enjoy looking at adverts on the Paris metro now I live here, again mostly for shows/art exhibitions/music (but also partly to absorbe French culture).

I work in marketing / previously worked in more direct advertising, yet most of the time find adverts annoying. But not on the underground.