Ethics

It is not uncommon for merchants to offer a slight discount if a consumer pays with cash instead of a credit card.  But suppose someone is doing work on your home and offers to give you a particularly sizable discount ? say 10% -- if you pay in cash.  And when I say ?in cash,? I mean in cold hard cash, not by check.  And suppose the amount of money at stake is thousands of dollars and not just a few dollars. 

The cynics among us (and perhaps you don?t even have to be cynical) might suspect that the person wants cash in order to avoid paying taxes on it.  Let?s assume that you suspect that this is the motive, but you have no other evidence to believe that such a motive exists other than the size of the discount and the request for actual dollars and not a check.

As a consumer, do you have any legal duty to refuse the discount and pay in a more traditional manner ? check or credit card?  Assuming you have no such legal duty (I am not aware of any, but I could be wrong), do you have any moral or ethical duty to refuse the discount if you suspect (but do not know) that the person is seeking payment in this way in order to evade taxes?  Should a lawyer be more reluctant to pay in cash in this situation than the ordinary consumer?