Yes, you can but you need to establish: how sound the artex background is as it can sometimes of been artexed twice and may have lost it adhesive qualities in extreme cases causing it to delaminate it can also have been water damage and so on causing the substrate too perish the weight of the plaster and the loose background inevitably causes the fresh plaster too hit the deck
In this instance, resheeting and putting up a false ceiling is your only alternative and also worth doing especially if it is uneven - shiny and a non pourous surface.
Shiny surfaces can also be problematic too simply polybonding these surfaces is not normally always enough
Hope this helps??
You can ; best way is to scrape as much as possible and to apply 2 coats of PVA with 24h drying time between. Almost none of the plasterers will do this though due cost related, so in some cases it might peel off.