"Does simply 'donating' away the bribe money from a scumbag make it all OK?"
Sure. It does if there is no way the person receiving the money could have known that it was donated in exchange for some positive action on some matter.
This is going to lead to a close look at the dates of the donations and any votes or other actions favorable to the donor.
If you have a donation, followed by a vote in favor of whatever the donor was advocating, then it's likely to cause a real problem for the person accepting the donation.
This story is going to have long, long legs in this election year.
The problem is it's difficult to distinguish donating money in order to get a politician to support your legislation from donating money because a politician supports your legislation.
You really need to see what's in the email record and, as you said, check out the dates of contributions and any change of support and see if there's a connection or a pattern.
An honest politician could hear out a lobbyist, agree that his legislation is worthwhile, then receive a donation since he's now a supporter of that legislation. If I was in elected office I'd take care to make very clear to my constituents the reasoning behind why I was voting a certain way, particularly with any changes in positions.