i've never heard of it. but what size cage do you have? what type of litter do you use? do you use fabrics in the cage? what types of toys are in the cage? how often do you clean the cage? how often do you do a deep clean of the cage? what do you use and how do you do your deep cleaning? how many rats do you have? male or female? do you bathe your rats? if so what do you use to bathe them and when/how often do you bathe them? all these things can have an affect on the odour in the room. perhaps changing one or more of them can fix your odour problem.
the current cage im using is 16x12x24, i use care fresh and fabrics in the cage, as far as toys go there is a couple of tubes a hammock and igloo and a chew toy, i clean the cage once a week just cleaned it on friday, ive only had the rats for a couple weeks havent "deep" cleaned the cage yet, when i do, ill use a bleach solution, i have 2 female rats, havent given them baths since they smell okay.
maybe i just have a real sensitive nose, its not that the odor is foul, i just don't want any odor at all especially when i have guests over
if its endorsed by kims ark it should be ok. they're pretty good with their rats.
the cage is too small for two (just large enough for one) so that can certainly add to the smell problem (http://www.rattycorner.com/odds/calc.shtml). carefresh should be pretty good about odour but i've found yesterday news to be the best litter for odour control. if the chew toy is wooden it can and will hold odour though after two weeks it shouldn't be that noticebale. but if you wash your rat laundry in a washer wih detergent then let it air out there shouldn't be smell coming from any of the fabrics.
in my experience though unless the cage is dirty you'd have to be right on top of the cage's litter to smell much of anything. though i do use yesterdays news and have a larger cage. mind you i also have more rats (7).
its up to what you decide to do but gettinga bigger cage, MAYBE changing the litter to YN and getting rid of wooden toys after they start to hold odour should keep the odour down to next to nothing.
i do have a larger cage that is 17"Lx24"Wx36"H, but they are still small enough to sqeeze through the bars, as soon as they are larger enough i will be transfering them to the larger cage. i have noticed that yesterday's news has variations is there a particular type that are more suitable for rats?
I had carefresh for a long time and YN is MUCH better. Plus it's way cheaper than carefresh. I'd go with the unscented to be safe and as far as the texture... I can't find the softer kind around my area but my girls don't sleep down in the litter, they sleep in cuddle cups (SO CUTE BY THE WAY) so I'm not too worried about that. I still have some carefresh left so I've been mixing the 2 so if the girls want to take the soft carefresh for a bed they still can. but I do like YN way better for odor control.
the unscented kind seems to be the easiest to find and is best for the ratties lungs. if you can get it from a feed store instead of a petstore or grocery store you'll often get twice the ammount for your money.