Rachel the Blue and Gold Macaw loves getting sprayed from a water bottle. Marianna sprays mist on and around Rachel and Rachel just soaks it all in. She dances around her Training Perches with her wings flapping to catch the mist. This is pretty typical for a rainforest parrot. Parrots from dry climates on the other hand (like Senegal Parrots, Budgerigars, etc) don't really like to shower much.
While Rachel can get really excited about a shower, Truman the Cape Parrot prefers baths. Meanwhile Kili the Senegal Parrot and Santina the Green-Winged Macaw are pretty indifferent to water. Either they don't want to get wet and resist or at best they do nothing. They just never get into it like Rachel does but I figure that when they aren't mad about getting wet, that these are the times they like it.
The best way to get your parrot used to showering is with a gentle spray mister. Use slightly warm water. Squirt the mist above the bird and let it fall onto the bird. Avoid squirting at the bird directly unless it likes it. The important thing is never to use a spray bottle for punishment or make showering an unpleasant experience. As long as you keep it enjoyable, it will be a great activity for you and your parrot to enjoy together.
Here's a video of Rachel getting sprayed from a water bottle.
I've been a fan of water bottles rather than water dishes for parrots from the start. I never liked the mess that comes of a bird's water dish and have found the water bottle to be the best alternative.
The advantage of using a water bottle is that the water stays clean all day long as the parrot cannot dump anything into it. Additional benefits include that you can assess how much water is consumed and the parrot cannot “dunk” its pellets.
The disadvantages of using a water bottle include difficulty of conversion, potential blockage, more difficult to clean, potential bacteria in the tube, and inability to bathe. Luckily most of these disadvantages are only potential issues and not actual ones. The extra work involved in cleaning a water bottle isn't much but it sure beats changing water multiple times a day. Bacteria in the tube is only likely to occur if water isn't changed frequently enough or bottle is poorly cleaned. The difficulty of converting a parrot to use a water bottle becomes moot once the parrot begins to use it and continues to for many years. As for inability to bathe, you can occasionally provide a water dish for bathing opportunities or the parrot can cleverly learn to shower with water from the bottle.
If you use a high quality glass and metal water bottle system, you are unlikely to run into problems. First of all, being without access to water for half a day isn't catastrophic. But more importantly, these bottles are very reliable and you'll know there is a problem with the bottle before anything bad happens. You can see how much water is consumed, unlike a dish, because of the air pocket that forms at the top. If more water is gone than normal, there may be a leak. If no water is missing, then there is a blockage.
I don't think the bottles themselves are prone to getting stuck. Instead they are more likely to develop a drip with time. In 5 years I have never had a bottle get stuck but I have thrown out one bottle that after a few years developed a drip. The drip was not catastrophic. Even at the end of the day over half the water was still remaining in the bottle but after a few weeks I got around to replacing the bottle.
The most likely way a bottle can get stuck and not dispense water is if something gets lodged inside. This could either cause it to get stuck or to leak all its water out quickly. If a parrot is obsessed with dunking or has some weird ideas where to stick wood chips this could happen. Always watch your parrot's habits and do not rely on a water bottle for greater than 24 hours unsupervised.
The water bottle conversion process of teaching a parrot to use the bottle is straightforward and simple. What is difficult is the stress on the owner that is not sure if the parrot is drinking from the bottle or not. I think it is best to get the bird to drink from the bottle when thirsty, so I would recommend not leaving water overnight, allowing the parrot to eat dry pellets with no available water in the morning, and then offer water from the bottle. Either hold the bottle in your hand or secure it on the cage. Tap the ball to show your bird how it works and allow a drop of water to form on the tip. Hopefully the bird will beak around the bottle and realize that pressing on the ball releases water. I would repeat this process a couple times and then see if the parrot can manage on its own. For the first few days, you may want to offer water in a bowl briefly twice a day to check if the bird is thirsty or not. If the water level in the bottle is changing and the bird does not want to drink from the dish, you will know the conversion is complete and successful.
When it comes to cleaning water bottles, dish soap and some scrubbing with a bottle cleaner are the way to go. A good place to get the cleaning brush is in a baby supplies store. Often times you can find a baby bottle cleaning kit with a large and small brush and that works perfectly on bird bottles. To be safe, I boil my bird water bottles about once a month to make sure there aren't any nooks that were missed in the tubes.
Here's a video of how my parrots drink from their water bottles. Check out how they each have a different way of making the water come out. And then another video of how Kili learned to shower from her bottle since she rarely has access to a dish.