As tml616 said, if you want to make a doodad appear upside down, you have to use the object editor and make the pitch value negative, however this is a bit more tricky than you would expect. If you havn't already gone into the advanced settings of the WE itself and allowed negative numbers, then you will have to hold down shift while clicking the value, this allows the entry of negatice numbers. To get a doodad completely upside down, I believe the number you want is -3.15
Not entirely sure though.