I too can support with anecdotal evidence for that (my wife). One of her habits is browsing Facebook ads and she end up actually buying stuff from those sites.
Mostly fashion related as those are something you don't search for but an impulse purchase. Fb is mostly like window shopping or street shopping - you have no idea what you want but you like something and take it. I on the other hand if I have to buy something will google it or go to amazon directly.