Same problem here. The bees like the muck heap (horse muck) and the goose’s pool which is quite green at the moment (goose departed a few months ago at a very ripe old age). They like drowning in this and the hens water bucket so I have to place twigs and floating items in them which helps. I now have a dedicated sheep trough with lots of floaty items which seems to be working, They seem to ignore our stream which runs along the bottom of the garden. As Chris says – – a good marketing ploy – – muck heap honey!