That sounds a bit mean lol. Edinburgh (Scotland) is a small city with just a handful of good clubs with high quality girls that I tend to frequent regularly so don't wana get a bad rep for being a complete dick to girls. Anyways, I wouldn't feel good about using these sorts of tactics.
I recently met an advanced player (from USA) who gave me 2 really amazing tips (hope this helps others):
1. "Power of assumption" - just "assume" right from the start of the interaction that this is just going to be a ONS or a quick fling...that way you are projecting and communicating your intentions and feelings at a subconscious level to the girl and everything you do/say will reflect that. This is an amazing tip which could be used in other situations (e.g. even when approaching girl(s) - just "assume" rapport)! - It really "primes" the girl beforehand.
2. "Power of honesty - when applied correctly" (not being cheesy here LOL!) - Just be "honest" afterwards and say something like "you're such a great girl and I can't see myself settling down with one girl any time soon and I don't want to get attached to you or mess you around so...let's just be friends" - or something along those lines
These tactics work for me - hope it helps others
thanks for the replies guys!