Newer machines are going to rust, unless they are Speed-Queen. When the machine agitates, what will be splashed into the cabinet, the humidity levels during this time of washing will also be quite high. Not as bad as it would be using almost boiling water (that makes lots of steam), but still a problem, especially in salty or humid areas. 

Our old top-loader was already started to rust around the lid hinges when we got rid of it - and that was after it was left open following each and every wash! We only used cold-water at that point too, and it didn't experience salt or humidity, was inside all its life. 

There were other rust spots on this machine that weren't visible (inside cabinet, back of machine - we don't know about that, lots of rusty screws and lots of water marks back there...). For the record, that was a Simpson SWT802SA.

I was not suggesting washing in hot water at any point on this particular thread (although I do agree with Dadoes, and will cite my own experience below). Whilst I don't recommend Cold water (for the reasons above), I was simply stating some evidence we had gathered from our own/my experiences. On newer machines, using hotter washes will quicken rust problems, especially if there is plenty of steam!

Although, I am agreeing with Dadoes. Our previous machine was starting to get a smell about it when we got rid of it last year. I was concerned because "clean" clothes smelt musty and not quite clean. They looked it, but didn't smell like it. We were unable to use Hot water because our water heater was on the fritz at that point (Solar Water Heater, was not able to heat effectively) and the hot tap at the washer was going to be too much bother to replace.

With our Miele, we've not been sick with Colds or the like since August last year - we've used any temperature from 40ºC (104ºF) north, up to around 60ºC (140ºF), whereas before, a number of us caught 3-4 colds every year (even during the Summer!), which was a pain in the neck - and the machine doesn't smell either. 

I think the issue with your current dryer might just be that it needs to be taken apart and given a service - it may be clogged inside with lint, which would cause the drying issues you describe. The air hose to the outdoors (or wherever it vents) may also be blocked, or home to some "lovely" critters. 

Also, from what has been stated here a lot recently, it is probably wise to avoid the newer Whirlpool DD/BD machines, as they have been cheapened a lot, and a prone to failure. I've stated before that the one I saw operating was poor, to say the least. Steam train noise, VERY slow spin.

It would be wiser to get a SpeedQueen unit. Could I recommend an FL SpeedQueen? There is no heater, but you can wash in Hot, Warm or Cold, and the Warm cycle can have a Warm rinse (if you desire). It operates quickly, and water level is adjustable (Your posts seem to suggest these are features you are partial to) and you can add a 3rd or 4th rinse as desired. 

Thanks as well for at least taking the time to run a cleaning product through your washer and use hotter water every so often - you are at least preventing the buildup of bad smells.

A word of advice though: On numerous TL, thanks to EnergyStar, "Tepid" is becoming the new "Hot," Cool is the new "Warm" and Refrigerated Water is the new "Cold" (Okay, that last one was meant as a joke, but Cold is Cold on these. Some machines WILL temper the water to ensure good results if your water comes out of the pipes in cubes, not liquid).