tedster - 8:29 pm on Sep 29, 2012 (gmt 0)
these ones have penalities and worthless backlinks
That definitely changes the situation for the worse. If you owned those penalized domains, then you can't ask to have the previous record reset to zero, the way you can with a change of owner. And to claim to be a new owner of a domain that you then 301 is very suspect, too.
You're playing with contaminated goods in a case like this, and you can easily spread the contamination. It's better just to dump the contamination sometimes. Swallow the loss and move on, lesson learned. And still keep an eye on the penalized domains from time to time. They can recover just based on time alone - but it can be years.