I have a Burmese friend (DTV holder) who did a border run to Vientiane last month. When she came back in through the land border gate, she was sent to a room and questioned by a "supervisor" IO on what she's gonna do, where she lives, how long she's gonna stay in Thailand. She didn't have to show any documents or bank accounts and finally let through into Thailand but she had to wait for about an hour to be questioned by this "supervisor".
At least for the burmese, the Nong Khai-Vientiane land border is getting stricter.