I use vinegar as a softener a lot of the time - anytime with wools or towels, and a lot of times with any other loads too (although I generally use softener with sheets - I like a lavender softener). It does help keep the machine clean too. I usually use about 20 drops of tea tree oil in with the vinegar as well.
I am not great at remembering to clean the washer, but it's usually ok.
But the filters on the condenser tumble dryer are another matter! The lint filter gets cleaned after each load. But I also need to remember to clean the lower down filter (condensing one) every couple of months, as there is fluff and lint that gets pulled down there and builds up. And the section from the lint filter to the condenser filter can have a build up of tiny fluff that is damp so sets like concrete on the edges and must be scraped off. I use pot scrubbers on the hard stuff and a long skewer to get into the condenser filter to pull out the bits that gather there.
We use vinegar in the coffee machine too. It does help.
And for teapots that have heavy tea staining in them, my Mom had a trick from years ago to put some biological washing powder in it and fill with hot water, leave for a couple of hours and come back to icky water but a gleaming teapot. A colleague in work, who has a tea mug that gets badly stained, uses the breadsoda from the office fridge - a pinch of that and his mug filled with water for a couple of hours works well too. (We keep an old coffee jar lid upturned in the shelf on the door which has a couple of tablespoons of breadsoda in it - as we had a problem with odours a couple of years back - and only realized at Christmas this year why the level had dropped to almost nothing when he admitted his extra use for the soda!! Luckily odours are no longer a problem).