We were without a dishwasher in my house for a month and let me tell you it wasn't fun. My wife isn't too keen on dirty dishes piling in the sink or on the counter. Considering that my cat uses the counters, tables and furniture as her own personal raceway, I wouldn't want to be without them either. Once thing I will tell you is that we do not have a top of the line model. It's an Amana Five Cycle I got at Menards for about $180 a year and a half ago. Of course, this model is N.L.A. in any store and the next best thing is going to run you about $300. Our dishwasher does a fantastic job of cleaning dishes as long as we fill the water softener with salt. There are others that are going to be lower priced than this, but even the higher end models made nowadays are going to suffer with longer cycles and poor performance if neglected or misused. Without the right maintenance, cleaning, rinse aids and soaps they will not clean your dishes.
The right soap (or detergent) is the most critical, and I'm going to go on record to say that many store brands may or may not work. The name brands, such as Finish and Cascade tablets will work the best. This is because they contain an enzyme. Other, cheaper brands will use silica and bleach. These are great for removing stains, but cleaning dishes is going to be hit or miss with this. The reason for detergent issues were that a few years ago, the Feds outlawed Phosphorus in detergents. It does a great job of cleaning, but is impossible to remove in water treatment plants. Phosphorus depletes dissolved Oxygen in the water, which leads to killed fish and algae buildup. Since then detergent manufacturers have been trying to keep up with this mandate. In this case, you get what you pay for. Buy the cheap detergent and pay the price with dirty dishes.
Rinse aids (they should be called drying agents) are mandatory, so use them. You can probably get away with a store brand in this case, but a name brand might help depending on the quality of your water and what you do to condition it. Our water isn't the greatest, but we use a store brand and it works fine. A rinse aid keeps minerals and other impurities from setting back on your dishes. Without it, they will likely spot up.
Water temperature is very important to dissolve the detergent. If it takes you a small eternity to get hot water from your kitchen tap, it's going to be the same with your dishwasher. Some will stop the cycle until they've heated the water enough to use. As most modern dishwashers have a smaller element than older ones do, this could add up to a day to get the water hot enough. The best cure for this is to run the hot water from the tap until it is hot enough and then run the dishwasher. You may want to adjust the temperature on the water heater. See your owner's manual.
In days past, most dishwashers had a chopper installed to help break up hard food to an extent. What they won't do well with are woody, or fibrous foods that will not only clog up the chopper, but may even clog impeller on the drain pump. Excessive grease will also cause problems as will poor water quality. Nowadays, dishwashers have a filter that needs to be cleaned every time the machine is run. This is to cut down on noise and save energy. If you don't clean this filter, your dishwasher won't be able to clean and drain properly. See your owners manual to see what yours has.
The most preventable problem comes from dirty water draining in from the garbage disposal or drain. The best way is to either install an air gap on your sink, or simply loop the drain line above the disposal. This is an installation problem that I've found a lot lately, including the installer of the garbage disposal failing to remove the knockout plug. Hey, it happens. Hopefully, this helps you before you have to call in a service person. There are a lot of issues you can have, but these are the main ones. Maranatha!