Why did "Joe the Plumber" ask about taxes on someone making $250,000?

This is not as simple as it may look. Lets divide this difficult question into several simple ones.
Does "Joe the Plumber" make $250,000 a year?
No, he does not!
How much does he make?
Apparently, he makes somewhere around $40,000.
Will his taxes go up under Obama's tax plan?
No. Currently, he does not make that much.
Does "Joe" pay taxes at all?
Hard to tell. Depends on how big his family is. If he is single he may pay up to $4,300 in federal taxes (as in 2007).  If married  with 2 kids younger than 17 he would pay 0.

From what we see, "Joe the Plumber" as he is today does not have to worry about taxes on people making $250,000.

Then why did he ask his question?

Why did "Joe the Plumber" ask his question? Part 2.

"Joe the Plumber" does not make $250,000 and pays very little, if any, taxes. So what? He said that he wants to buy the plumbing business that he works for now. And being such a great entrepreneur as he is (currently making $40000?) he thinks he will be making $250000 in no time! Do you think this is possible?
Very few plumbing/HVAC businesses in US sell for the amount of its annual profit (data compiled from http://www.businessesforsale.com/). Usually, price is at least 3 times the profit. Assuming Joe's company generates between $150K and $200K in profits, he should expect to pay at least  $450K.  With his income of $40K he can hardly come up with such a sum. What if he takes a loan? He will probably need a 10% down payment - $45K. If he will get the loan for remaining $405000 at 7% for 10 years, he will be paying bank $56,500 each year. This payment will effectively decrease his profits from $150K to below $100. How long it will take our "Joe" to double his business? Even if he is the best, the luckiest plumber alive? A year? Two? Ten? In this economy? You tell me. But remember, he is still well below that $250000 number.

Most likely, as a plumber he will never be making enough money to be affected by the tax increase proposed by Senator Obama. This is no surprise, since according to US Census bureau in 2005 just 1.5% of American households had income $250000 or higher and 5% had income $167000 and higher.