I recall there were quite a few experiments where people use certain keywords heavily just to get closely related ads later on. I can totally relate my experience with it as well. Of course it is inconclusive - but if there is an incentive, management of big companies will venture into it. And chinese management is no different from western ones to that matter.
It's been a while since I browsed anything without an ad blocker.
Do you still get ads for the exact thing you just bought for a week after buying it? :)
They don't pick the keywords uniformly randomly from a list of all keywords though. They think they randomly picked something that popped up in their mind, but those keywords are either
- stuff they saw online recently — ads or otherwise, which put the keywords in their mind
- or stuff they were already interested in recently
Not hard to imagine targeting algorithms picking up on either of these