What's the risk of my bees collecting yucky substances from the neighbors - e.g. from old soda cans, antifreeze puddles, or worse?
That's a good one never did think about antifreeze.
If I found out some one in my neighbor hood was leaving stuff like "anti-freeze" sitting around.
I would either do some action or have some official look into the situation.
It will kill an animal, dog, cat, etc.
I don't think a little soda will hurt, no more than is left in a coke can.
As for stagnated water, well, my bees prefer it over fresh water sometime. Why? I don't know.
doak
I've heard at a lecture that bees may tend to go to "dirty" water rather than fresh clean water because there may be minerals present that they need. Makes sense to me.