From what I'm seeing most of the USA ass-licking countries still have all sorts of regulations against SL while other countries have made things better for us in the last 5 years.
So to be in the safe side I think we really need to get perfect paper work + extra docs to prove your visit, and sufficient financial background depending on the country you are visiting.
As for Sri Lanka being sorta blacklisted, I think it's because some of the Sri Lankan's doing crazy ass shit when they are overseas as well as Indians trying to pretend as SL and doing crazy shit. (I have seen myself, Indians wearing turban claiming they are Sri Lankans and approaching people in shopping malls and asking for shit.) I have already informed SL authorities but no one got back to me, as expected!