Two examples:
I'll call this "Spinkles" - A state with low average income (we'll use WV) voted for Bush, therefore, poor people voted for Bush. A state with high average income (we'll use MA) voted for Kerry, therefore rich people voted for Kerry.
I'll call this "Bastet" - A state that has low average income but votes for Bush (overall) does not mean that poor people voted for Bush at all. It is very possible that whatever rich people there are in WV (every state has a certain percentage of rich voters) all voted for Bush. The rest of the population was probably split almost evenly - the poor religious right voting for Bush and the poor people that can think for themselves voting for Kerry. Thus, Bush carries a "lower income state".
I'll save the typing, but you understand the concomitant argument for rich states (I hope).
Reality:
Without clear factual data showing each person's income and how they voted, we can only guess whether the assumption made by Spinkles is correct (poor people vote for Bush) or the assumption made by Bastet - that rich people vote for Bush and that they got just enough help from poor religious people to put him over the top, is correct (if either - there are other possibilities).