My first XPS had a fun little design quirk where the laptop display itself obstructed the (single and only) exhaust vent.

Out of the factory, the airflow was acceptable, but after a year of use and dust buildup, guess what... the laptop would overheat!

Double whammy -- the air that _could_ get through was so hot that it would also deform the part of the screen that obstructed the vent.