The figures I've heard and read are that maybe 10% (20% at most) of the registration forms ACORN has turned in over the last year were invalid, for various reasons, mostly clerical errors (names misspelled, addresses written illegibly or inaccurately), addresses having been changed within the state, or the lack of an "exact match" between identification documents (as required by HAVA). Many of the registration applications initially rejected are subsequently accepted when such discrepancies and errors are cleared up.

The number of patently fraudulent applications -- people long dead, businesses, cartoon characters, multiples of the same name and address, etc. -- is a very, very small percentage of the applications turned in.   Certainly not worth disenfranchising a lot of legal voters over.