Toads: Symbol?

This poem was very hard to understand for me. What are the two toads symbolizing in the poem? The speaker describes one toad as soiling "six days of the week... with its sickening poisen just for paying a few bills." Is the toad money and greed? This is the only thing that makes sense to me, but throughout the rest of the poem, I struggled to come up with any examples or text supports to prove this. The speaker describes poverty through depicting "nippers [that] have got bare feet." However, I have found no direct connection between the toad and this description. The second toad is described as "hard to lose" when both toads are present in a person's life. However, I'm clueless what this could be. I'm interested to hear what other people think these toads symbolize in class.