Taximeter from airport Suvarnabhumi are allowed to charge 50 Bath extra by government. So that has nothing to do with a scam.
If you want a taxi from Pattaya to Suvarnabhumi, you will pay about 1000 Baht, which is 200 – 300 Baht LESS then on the meter. So sometimes negotiating is interesting.
About all of the mentioned scams can happen all over the world. It is good to be aware of them, stay alert, but don’t expect that everyone will try to scam you.
It may take weeks before you are confronted with one of the mentioned practices. The problem, in my opinion, is that it is so UNcommon, that you might not be that alert after a few weeks without any problem.