Ah, I think Transpac is exaggrating a bit. The trains have deteriorated, but human waste, southern insurgents? Sounds like someone with an axe to grind.

I visit Thailand every year and always use the trains. They are a cultural experience for sure - you get to rub shoulders with the locals, not just the ones that work in "foreigner facing" jobs. I prefer second class non-air conditioned (fan) sleepers at this time of year - fresh air in your face. But take a lock to tie down your luggage, I have seen bags stolen from 2nd class carriages.

My wife is always on my back to use the Nakhon Chai Air buses, but there is something about travelling by train that is special - something that many people just don't get.