In my opinion, "messed-up" (with a hyphen) is how you would write the adjective, and "messed up" (without the hyphen) is how you would write the verb.
This is a messed-up xxx.
I messed up the xxx. / I messed the xxx up.
I don't think there's a steadfast rule about the hyphen, however, so I imagine many people would write "This is a messed up xxx."
As for "verpfuschte Arbeit," I suggest:
(a) botched job
a botch job