Yep, I guess it was an inevitability. A new Facebook Messenger update is on it's way and it looks like we're being treated to some targeted advertising there too.You should be able to hide the ones that aren't for you, but that will just be replaced with yet another one and so on and so forth...
Businesses won't be able to contact us directly via messenger, unless you start a conversation with them. It's being trialed across Australia and Thailand and will probably be with us in the UK before we know it. Most adverts don't bother me personally (too much) But I can see a lot of people really disliking this move.
There have already been over a billion messages sent back and forth via the messenger service, so it's a pretty huge way to drive their sales. Personally I think it will get in the way, as well as looking like one of those pages that make you wade though loads of adds before getting to the point.
"However there is a way of avoiding the messages - and it all depends on how you've used Messenger in the past.
The bots will only be able to send out sponsored messages to users that have messaged them in the past requesting information." - Source