Read the specs and warranty carefully - some are not intended to be anything more than a powerful hose. They will have 'warranty words' like "for household use only" etc etc. Some will have a recommended time limit for use. Choose careful/appropriately for your intended use - not all washers are born equal.
Despite advertising and pretty pictures on the packaging they are not washers or cleaners - on a dirt bike you will still have to get in there with a brush and detergent to get stains and grim off. Pressure 'washers' are great for getting general build up of mud etc off - you will still have to get in there with elbow grease to get things clean. People do damage when they try to use the 'washer' to get rid of every bit of dirt rather than getting in there with a brush and elbow grease. That's when they use concentrated jets in and around wheel bearing etc.
For some jobs the pressure washer is unbeatable. I have several large outdoor tiled areas which I clean from time to time with the Karcher. The Karcher uses one tenth the water a hose would and does tens times the job a broom or blower would. The pressure washer gets between the titles and bricks and gets rid of dirt and moss not only making it look a better job but also stops long term structural damage of weeds etc
My Karcher is nearly 20 years old and it has run continuously for 4 and 6 hours at a time cleaning roofs etc. It is so old it has brass fitting through out
.