This isn't a scam. This would be a huge step up for most US properties (read: especially W Hotels). Of course it might be better if they gave you 24 hours notice before running the charge, but the longer they wait the higher the risk that the charge might decline, and some minibar tabs can get out of this world. By notifying you the same day they run the charge, you have the opportunity to fix a potential error before the charge actually posts to your statement, avoiding any real problems, as long as they timely fix the error. I don't see any problems here.