I suppose there's always a risk you've just got to use good judgement, I think you can usually tell if someone is absolutely hammered or just a bit drunk.

And even if they change their mind the next morning the fact they were happy to go home with you etc means you'll unlikely get convicted because there's plenty of evidence to show the consent was there. Sneaking into a hotel room during her sleeping with someone else and joining in without even meeting her prior is not something I've done, that's where the risk lies not the sleeping with someone who's drunk.