I answered your post about nail trimming on your other post, but as for the bath topic, here is what I can tell you.
I really have never seen the need to bathe your rats. If your rats are kept in a clean environment, and their housing is regularly kept clean, there should not be any problems with your rats being "smelly" or needing any type of bath. In addition, rats are actually very clean and they are meticulous groomers. They spend a good deal of their time "bathing" themselves and grooming, so they are very clean animals.
I have never had any issues with any of my male rats needing an actual bath, so that is my personal opinion on it. I think the people that complain about their rats' "smell" is because they are not keeping their cage housing clean enough and after awhile the urine can build up, which is also not good for a rat's sensitive respiratory system.
As for baby wipes, those are a TERRIFIC item to keep close by! Once in a great while, very rarely, but sometimes, my boys might have been lying down right over a poop or something, and they might get a tad "ripe" smelling and this is where a baby wipe can come in handy as a great "sponge bath" so to speak, and without the trauma of an actual bath.
If you get one of those plastic tubs of baby wipes from the baby supply aisle at your local grocery store or drugstore, get the unscented ones that do not have any perfumes, etc.
Those baby wipes will come in so handy as a quick way to give your ratties a quick wipe down when it is needed. Just a quick swipe across their backs and rear does the trick. Starting at the neck and swiping down across the back and towards the bottom area. I don't need to do this very often at all, but there is another great use for the baby wipes as well: I use my baby wipes almost every day for a nice way to do a quick wipe down of the platforms and surface areas of my boys' cage. It is an easy and quick way to spot clean the surfaces and I know it will not harm the boys' noses with any harsh smells or chemicals.
Lots of people on the forum love using baby wipes for quick spot cleaning in cages, and, once in awhile, if you feel your boys have a bit of smell or if they rolled in something icky, you can do a quick wipe on your rats with the baby wipe. They are the best product ever for rat people!
Hope this helped a bit?