If you do use one just be careful with it. In my industry it was common (stupid) practice to use one to clean dirty boots. That stopped after some idiots sliced their toes off. I know the DIY versions are less powerful, but hit someone in the face with the jet, just because you turn round to talk to someone, will cause damage. Also make sure the pressure has all been released before disconnecting the hose.
As mentioned the jet can lift logos, mastic etc, but it can also easily get in through the windows and you can have a nice wet mess inside. I would prefer to use a garden hos with a spray nozzle for the job. As also mentioned a good cleaner such as 'Muck Off' will do the job nicely.