For thousands of homeowners struggling to keep up on mortgage payments, there is the added difficulty of falling behind on property taxes and having to deal with opportunistic companies that have taken over tax collecting for local governments. Numerous cities and counties have sold their delinquent tax bills to firms willing to take the risk of collecting from deadbeat landlords or average homeowners fighting to survive the current economic recession. This move has given local officials an infusion of cash to pay for schools or public safety programs, but it has left property owners at the mercy of private collectors who may be exacerbating the foreclosure crisis.