There was no good way to determine if their site was good or not.
I suspect that for many of these large commercially developed sites the base quality level of the security is about the same. But sites in favor with the left and the government don't get hacked, except when they do like the DNC (maybe) or John Podesta, and then the "hacking" gets blamed on Russia. Search 2016 email hacks if you want to see Google and the main stream media's copious spin and misinformation on that topic.
Sites in favor of conservatives do get hacked, which suggests that the hackers may be getting help from friendly spy services, or insiders at the various hosting and service providers.
You can see how aggressively the government prosecutes opponents who hack them or their friends. I wonder if they will be a zealous going after the hackers of GiveSendGo. I'm not holding my breath.
It probably is not the underlying code of the site, just which side it is on which determines how likely it is to get "hacked".