Because my cousin just reminded me of this awsome surprise about them. The form fitting of the butt causes less room in their diapers and if DD pooped in one, that poop would travel out every opening in her onsie or pants, or whatever she was wearing, including the neck hole. Luckily they are easy to clean.

Just felt like warning you all.
Re: PSA about bumbos
9/13/09-Twin boys born at 23 weeks due to Pprom.
Ethan and Jacob-our beautiful angel babies lived for 11 minutes and 23 hours.
Single embryo FET 12/2009-BFP! Blake born 8/2010 at 39 weeks after 36 hours of labor and an emergency c section < IVF 2- BPF! Due April 27th Our Story
BFP #2- 1/5/10- Baby Jack born at 37w2d, 6lbs 13 oz, 8/24/10
BFP #3- 7/30/11- Baby Boy Due April 3, 2012
I used the bumbo quite often with DD and never had that problem... but I guess it could happen. The seat was great IMO, and that is definitely not a reason to avoid it.
For DD, we didn't get a bumbo, but opted for this. It worked wonderfully bc u can buckle them in, and was easy to take with us when we went to visit family. She still uses it as her booster seat at our dinner table now.
There are several different brands of them and the prices vary. Kmart and Target seem to sell the biggest variety of them.