The agent has definitely used some sort of filter to bring out the red. That's really obvious in the picture of the balcony, the fences and the (tiny) bit of grass you can see are a totally different colour in the external shots
I think I'm correct that all the red was accessories/soft furnishings/furniture, so wouldn't be there if you bought it. But then you would end up with an entirely grey box, which to my mind is even worse (and I really hate the red with it). Honestly, these identikit grey mansions really spoil my fantasy house hunting - simultaneously utterly awful, but too extensive/nicely done to justify ripping it all out and start again.