Why I can't take money from unions

I have nothing against unions. I was raised union. My dad was a member of Sheet Metal Workers Local 2 for my entire life. I even earned a college scholarship from the national for an essay I wrote about growing up in a union household. What I do have a problem with is the appearance of impropriety. The kc buzz blog reported yesterday that local firefighters and carpenters unions have persuaded six county legislators to approve 6% raises for the employees of the Jackson County Prosecutor's Office. It is speculated that the moves going on at the county have to do with attempting to gain favor with the unions for upcoming elections. Union Political Action Committees (PACs) pour a lot of money into campaign accounts. A candidate who gets the backing of the unions gets a lot of money. To me this seems like a conflict of interest. Elected officials are expected to vote on union contracts having accepted significant amounts of money from those very unions. I'm sure any politician could rationalize and say they receive money from all kinds of sources and it in no way affects their objectivity. Maybe so, but why take the chance?