Lately, I've seen problems with some very basic instrument maneuvers, the hold and intercepting an airway.
My ATC buddies tell me the most often issued hold is an intersection hold, usually with a direct entery, or with a hold as published. During a checkride, I give a very simple hold (with plenty of time for them to figure it out) and for some reason it get messed up.
Intercepting an airway is anouther problem, especially with an IFR GPS in the aircraft. Note: It has NOT been a problem with canidates without a GPS. It seems that we get use to GPS direct to everywhere and that Airway tracking essential skill has been forgoten. Just a couple of months ago I was given "Turn left 20 degrees and intercept Victor 123 the Volk East MOA is active (Sorry, I forgot which airway).
As part of the instrument checkride, we start out on a simulated cross country. As part of the instrument clearance, I'll asign radar vectors to intercept a Victor airway. I don't care how the radios are set up, but the flight goes a lot smoother if they are set up on the ground. If there are any questions with the clearance, it's easier to ask on the ground rather than in the air.
So there are a couple of clues to what will come up on the IFR checkride. Good Luck!