I
wish there were bounties :-)
There is systematic checking - e.g. crt.sh continuously runs linters on certificates found in CT logs, I continuously monitor domains which are likely to be used in test certificates (e.g. https://bugzilla.mozilla.org/show_bug.cgi?id=1496088), and it appears the Chrome root program has started doing some continuous compliance monitoring based on CT as well.
But there is certainly a lot of ad-hoc checking by community members and academics, which as Sleevi said is one of the great things that CT enables.