Stone's a slime ball, as are many individuals Trump pulls into his orbit. Given the calibre of his criminality compared to most of David Schoen's other clients, however, he's almost a saint by comparison. Not surprising Schoen agreed to represent Epstein in 2019, shortly before his death, given the reprehensible figures he always tends to take on as clients.
With respect to Bruce Castor, though he claimed during Cosby's 2016 criminal hearing he didn't have sufficient evidence to prosecute Cosby in 2005, I call BS on that and think his position at that time was purely political. During that hearing he further went on to state how he'd cut a deal with Cosby, declining to press criminal charges against him on the assurance the latter wouldn’t plead the fifth during the civil suit Andrea Constand filed against him.
Not even the Judge in that case found Castor's claims believable as he provided no evidence of any written or oral agreement between himself and Cosby and as such, determined Castor's testimony to be inconsistent and not credible.