With my fair and balanced hat on. ATC can either say descend 4000' / climb 5000' or if they use the word "to" then they should add either Altitude or Flight Level before the numbers. Descend to Altitude 2500' which is supposed to remove any confusion over 2 or "to".
I know what their supposed to say iceman,
But they are increasingly saying descent TO 8000 ft etc. Listen out on your next arrival.