One of the new slides I included in my presentation lessons for entrepreneurs deck: talk about the elephant in the room. Some issues are just so obvious that you have to address them (Mark Suster gives a few examples here).
OK, you can decide to ignore them. The potential investor will say "thank you very much" and mentally shelf your pitch already while shaking your hand on the way to the door (peaking over your shoulder to that enormous animal standing in the corner).
Image via David Blackwell