Every bloody time (aka "why do I not learn?!") 
For the past few years it's been The Walking Dead. On a Monday they would publish either a plot-spoling photo and/or caption after the US broadcast.
And now they've done it with The Handmaid's Tale too - revealing a fairly significant plot twist happening in a future episode, so not only do they spoil current episodes, but also later ones (this time I avoided the site till after I was caught up, and it's STILL been spoiled!)
And they don't only put these spoilers in the dedicated TV section that you can carefully avoid, they are right there on the homepage so you just scroll into it without warning.
3 years running I complained about them spoiling the zombies and got exactly (almost word for word) sorry-not-sorry back. They are showy offy look how much we knowy bastards.