Conversation:

Honey made from rhododendron and azalea flowers is to be avoided. It causes severe sickness, dizzy fits, and hallucinations.

If you eat it you might be well and truly mellified.

...but how would you know where the bees had been tramping?

That thought's struck me before. No doubt rhododendron pollen is involved in quite a lot of honey. Presumably there's a certain 'critical mass' that has to be reached before any ill effects arise.