Scenario 1.  Pilot shows up in a Cessna C-162 (Skycatcher) for a private pilot checkride.  Pilot weighs 225 pounds, DPE is 180 pounds and the fuel tanks are toped off.  Pilot presents a weight & balance with the airplane within CG but clearly above Max Gross Weight.  When asked about it, the applicant says "My CFI is 200 pounds and the airplane flies fine"

Scenario 2.  Commercial pilot shows up for his multi engine checkride.  Shortly after take off the right engine oil temp goes above the red line and does not go down when in cruise.  Pilot said "it always does that and the mechanic says it's OK."

Scenario 3.  Initial CFI applicant flying a Vans RV-12.  During the run up the pilot notes the engine is running hotter than what he normally sees.  He hasn't flown this particular RV-12 before but its running hotter than the one he usually flies.  Pilot discontinues the run-up and returns to the ramp.

Scenario 4.  Commercial applicant flying a DA-40.  As part of her preflight, she sumps the fuel into a plastic jar and puts it into the baggage compartment (yes the jar is 1/2 filled with fuel).  When asked about that she responds with "that's school policy".
 
All four of these scenarios are real and have happened in the last 6 months.   

Last year I did about 60 initial CFI check rides and this year is on track to beat that!  Since January, I've done 19.  As you well know, an examiner is required to test the knowledge test codes missed on the knowledge test.  I'm seeing a lot of initial CFI applicants missing the same questions on the knowledge tests.  The 2 most popular Tasks are Navigation and Cross-Country Flight Planning (specifically AI.II.K5)  and Performance and Limitations (specifically AI.II.K2e).

These will get added to the check ride in a scenario.  For example, "we are to the point of planning our students first ever cross country.  Pick some place you want to go and teach me how to prepare the cross country" or "Teach me how to prepare a weight and balance for our flight with you, me and the 35 lbs. of crap we have in the baggage compartment".  Notice how I leave everything up to you.  Im the student.  If I haven't assigned the Task before the check ride, I'll give you 15-20 to prepare something.  

So here's a few suggestions to help get through this successfully.  1. Be really familiar with the subject matter missed on your knowledge tests.  2. Prepare and use lesson plans developed as part of your CFI training.  I found the best applicants prepare their own lesson plans but it is ok to use commercially produced ones (just go in and modify them for your own use).  3. Use the Private, Commercial and/or CFI ACS to insure you cover the elements needed.  

Here are some common errors Im noticing:  

Cross country planning: 1. Using Magnetic Course in place of True Course.  2. Not correcting to a common measurement (example the airplane POH is in MPH and the distance obtained off of the sectional was in Nautical Miles or when determining ground speed and cross wind correction using an TAS in MPH while the winds aloft is in Knots). 3. Not applying Deviation.  4. Not applying Notes from the performance charts (example reduction of cruise speed for missing wheel pants.

Weight & Balance:  1.  Not being able to find a current weight and balance in the POH.  2. Using a sample aircraft weight and balance and presenting it as "the real" weight and balance.  3.  Being able to define terms.  4.  Using a "cheat sheet" but the information on that "cheat sheet" is incorrect. 5. Being able to describe the "why and how" operating outside the CG limits is unsafe.