I was too lazy to find the citation, but since you challenged me...
"Most modern SSDs come with some form of hardware encryption. On these drives with hardware encryption, itís usually permanently turned on - all data written to the NAND is typically stored in encrypted form. This stems from the fact that all writes to NAND had to be scrambled to begin with (writing long repeated strings of data to NAND can cause problems for data retention)."
Phew, I'm right. As usual. :-D