There aren't any bugs in formula per-say. It's that formula isn't able to be "sterile" so it is advised to use boiling water just in case. However so much care is taken when processing formula that bacteria residing in it is unlikely. Using room temp water goes against guidelines but I weight it up like this. I KNOW my baby will get very upset and distressed if she had to wait for me to boil water, wait 30 mins before adding formula, make her bottle and then wait for it to cool each time she needed a feed (It's also completely unrealistic to do that in the real world, especially one with a toddler too). So I weigh up the definite result of her getting extremely upset and distressed with the very unlikely result of her getting a dickie tummy. We all have likely read about how negative it is to let a baby CIO, due to the effects long term crying can have on them. Letting a baby cry long periods to wait for food is the same for me.
I've done room temp now with both and was able to ensure neither had to really cry for a feed. I'd know when it was due and be able to have it ready straight away, even at night.
Though, as a Mummy, you have to weigh up things yourself and make your own choices based on how you prioritise risk etc. There's no right or wrong really. I've spoken to MANY health visitors and midwifes who have ALL given their own suggestions on how to prep formula and not one was to follow the guidelines to a T xxx