If you get in a pinch you can always clean it with ice and salt. A long time ago when I used to work in a restaurant, we used to clean all of our coffee pots this way - fill up about 1/4 full with ice cubes and a healthy dose of salt. Let sit for a few minutes to get an ice-salt slurry, then swirl around in the air for a few minutes. They always come out crystal clean and shiny.
I just picked up a 5 liter Pyrex erlenmeyer flask for 10 EUR, hell of a deal. I'll be using the above technique tomorrow to clean it since it appears that somebody has been using it as a flower pot or something.