What you say is correct from al the perspective of advertising and corporate budgeting. From the perspective of charitable work, which they invited by loudly proclaiming "look at our charity", it is appalling.
They weren't touting their charity. They were touting their charitable franchise owners. That's a major distinction.
Imagine if Google made an ad saying "We donated $50,000 to charity. Look how generous we are. Come work for Google". That would be nonsensical.
Now imagine if Google made an ad saying "Joe is a Googler. Joe donated $50,000 of his own money to charity. Look how wonderful our Googlers are. Come work for Google alongside people like Joe." Very cheesy, but it makes a lot more sense. Domino's ad is the latter, not the former.
Personally, I find all non anonymous charitable donations in poor taste, and that reflects badly on Dominos for someone thinking like me. But for those receiving charity, surely any amount greater than $0 is enough, since it is a charity.
Also, nobody is under any impression that Dominos is a charity and not a pizza joint.
As an aside, some charities are scams, but many are not. There are tools you can use to determine which ones are trustworthy, but some basic common sense goes a long way too.