2008 VW Jetta. Rear headlight has condensation and trunk has foul ordor.

If the car is still under dealer warranty go back to them. Water entering the trunk is causing the odor. If left uncorrected the it will eventually cause rust or cause poor electrical connections. Water may be entering through a trunk seal, rear windscreen seal or tail light.

I am guessing you mean rear Taillamp. If there is condensation in it, then the seals are most likely bad. You will need to replace the entire assembly. Only other thing would be a small crack in the outside of the lens, but the lens comes with the whole assembly anyway. If the trunk has a foul odor and your vehicle has a sunroof, check the rear drains to make sure that they are not backed up and leaking water into the trunk. Also check the wheel well area to see if water has pooled up in there due to a clogged drainage problem.