Can a revocable trust be sued by credit card companies after the person is deceased?

That all depends on the trust and whether it was set up properly to protect the assets of the decedent. In order to transfer title to property out of an individual to protect that property from probate and creditors EFFECTIVELY, the trust must be drafted by a professional. If the truster maintained any control over the trust the trust property may be vulnerable to claims against the decedent's estate. The creditors can make claims against the estate and a judge will decide.