IMO we are talking at cross-purposes, I brought my first set of golf clubs here as a tourist, no duty. Second set no duty, third 3000 baht. Retirement visa.
You may be right in saying you can bring in personal effects with no duty payable when you come here, excluding sporting equipment. However, does the exclusion mean you can't bring it in at all, or only that you have to pay duty assessed by a Customs official if you do?