From mountain biking? It's covered more or less in red sandy dirt and some mud on the downtube. The red stuff all over the components, chain, etc.
Is it bad to leave it there? I'm not riding it now. Use the road bike most of the time. When I finish building the new front wheel I'll ride it to work and give it a bath and cleaning, but for another say - 2 weeks - is it fine being dirty?