There's a catch with convergence funds: EU never pays 100% of the bill. Average is closer to 50%, I think, so it is enough to tempt politicians into unnecessary investments, and not enough to be completely harmless for local community budget (there are cities in Poland with debt to yearly income ratio of 80-90 %).
Theoretically, the not-100% rule is meant exactly so that the receiving state won't spend the money in completely wasteful projects. Unfortunately, this isn't a full assurance against the long term stupidity/short term greed of local politicians and voters alike - this happened in Southern Italy too, and surely in many other places.
