I have used in the past quite a lot with elderly or disabled bunnies who could not clean themselves efficiently. It is not ideal and they did sometimes go off their food for a short while but I live alone and was working 12 hour shifts at the time. I couldn't bottom check every couple of hours.
Over 20 years ago before I knew anything about bunnies one of my buns died of fly-strike as I had no idea what the maggots were, 'phoned the vet and was told to take her in that evening. When I got in from work she was dead and I have never forgiven myself and never will, knowing now what a horrendous death she must have had.
More recently, probably in the last ten years, I had an elderly bun who I had to bottom bathe occasionally. I checked her routinely, went out - fortunately not to work, came home three hours later and her bottom was crawling with maggots. I scraped them off with my nails, dashed her to the vet and she survived - but the speed at which the maggots spread horrified me.
At the moment all three of my buns are able to keep themselves clean and I no longer do such long shifts, although am still out of the house for 8 hours, so I don't use rearguard. If I had an elderly or disabled bun again I probably would use it when I had to leave them all day (which isn't every day any longer).
I know there are a lot of people against it - and I will probably be criticised - but I am being honest and, for me, in some circumstances I think it is the lesser of the two evils.
