if you get a bubbled area off quite easily.... then you can see the edge of the plaster and the lining paper underneath round the edge of the hole? so if you hold your steamer over this edge for say 30 seconds, and try and get your scraper under it, it doesnt budge, flake or otherwise?
it all depends on what you want, whether youre going to be happy with it or not.....
what im going to say goes against every rule in the plastering book... but if it wont come off with a wallpaper steamer (steam, as in hot water directly applied for a matter of minutes, followed by a good dig with a decent scraper) then its unlikely to come off in the near future.... (patronization not intended, just trying to illustrate a point)
so go with plasterer No. 2.... never going to be perfect, but will save you a lot of money..
if, on the other hand, you can loosen it.... then go with plasterer No.1... and pay some school leaver who doesnt know any better and could do with a kick up the preverbial anyway to spend a few days with the old steamer.... a good scraper would work wonders though....
good scraper