@Gooba: For starters placing some dirt overlays in corners and such could help to counteract the cleanliness, but that could be a bit too much force. Huckle does come up with a nice idea though, leaving several open panels across the place with a much dirtier pipe-infested area behind the clean front.
It could simply be that your base textures that you are use are a bit too clean for tf2. they're not noisy enough, and white walls just look like monochrome walls without any detail or noise in them from a distance. Most of the white brick, wood, and concrete walls have a certain amount of dirtyness and discolouration in them.
Those textures obviously don't really fit your theme because they're too dirty, but the flit side is that your current map feels too clean. not just hospital clean, but utterly spotless clean.
You could obviously use it as a sort of super-spytech theme contrasting to the 'normal' outside area. However, as a super-spytech theme, it still needs slightly more noise. not much, but a little bit.
Hope that helps somehow.