@Rogerio *****
well if you've never been asked, then it can't be true. Or at least you've not gone as far as to deny that very true fact, based on soley your experience. But yes, I can categorically confirm that immigration 'can' and sometimes 'do', but 'not always', ask you for the 'three proofs' of 20,000 baht or equivalent in cash, proof of accommodation booking, and proof of onward travel before visa expiry, and they can refuse you on any of these. That you haven't been asked, says that you must appear to thai immigration as a genuine tourist and give no reason for questioning, but those they don't like the look of, can be asked, and refused. It is written and printed and displayed in many immigration offices and check points.