From a germ perspective the items that need hot washes are those that come into contact with your arsehole and dirty hands - as that is where the germs are likely to be nastiest. Obviously, the same goes for anything that got D&V on it.
To really blast germs, if that is what worries you, then you need 60 degree wash and a strong detergent, ideally with some bleaching agent in it.
Any fatty stains also need a high temp to help shift them.
Protein stains need a cold wash first, otherwise you set the stain in a hot wash.
For bed linen that has only been on the bed a week and the occupants wear pjs, then you really only need to freshen it all up with a lowish temp wash.
None of this matters if the inside of your machine is manky and has a load of gunk in the rubber seal, breeding germs to spread over every wash you do - so make sure that's clean.
Sunlight is also a really effective germ killer, so ideally get your laundry out drying in the sunshine.
All that said and done, I wash darks on 30 or cooler, including pants and I wash whites on 40, including pants, towels, bed linen etc.
Once a quarter, I nuke the bed linen on 60 and use an oxy wash product at the same time to ensure they don't start to go grey.