I didn't really have a worst buy until recently - pretty much everything seems to do fine on ds.
Then last week I bought a Cushie Tushie. Talk about disappointed

it did look gorgeous when it arrived, but ONE prewash later the fleece was bobbly and looked old, the inserts went curly, the minkee outer looked kind of bedraggled and the nappy sounded all crinkly. One prewash and it looked like I'd had it for weeks

I have to agree with previous posters that the quality doesn't match up to the price tag. I could have got another beautiful Monkey Snuggles for less than the cost of this. Oh well, you live and learn. A lot of people seem to love these though
Then on top of that it was a bad fit. Didn't leak though so there is that.