It seems to be that going on the trial-and-error mode in the US is acceptable and does not draw comment nor frowns when one resells his/her bag, regardless of whether the bag is from the store or reseller.
In SG, that is NOT the case. We have to think very carefully if we want a particular bag or not. Mainly because demand for birkins and kellys are very high (we have a lot of tourists too) and supply is limited. That said, the stores did great sales last years, so supply *should* be more this year! Should a bag be directly from H, gets listed on eBay (unfortunately, there are customers who will act as spys and tell on the eBay seller), the customer is very likely to be investigated by H and be blacklisted. That's why I said money spent is hard to recoup. Because of the limited number of birkins and kellys around, the stores tend to be very quick to find out who actually owns the bags on resale.
I have a personal story to share, which I have never mentioned. I bought a Kelly from one of the H stores here, and found that I have the tendency to pick my birkins over my Kellys. So I thought I'd sell the one that I'd only used a couple of times, and send it to a better home.
From reading this forum, I was being naive and just dropped my bag off at a brick-and-mortar reseller's shop. I tell you, it was hell for me after that. The store found out (don't ask me how). My relationship with the store I bought the Kelly from nosedived. I took great pains to recover that relationship and lost sleep over it when I was still trying to sort things out. I took my Kelly back and never sold it. Hermes SG does not approve of reselling. Simply because when a customer buys a birkin or a kelly, that is one less bag in their inventory for the pool of customers still waiting for their bags. And it's not fair if the first buyer does not treasure the bag, and just casually flips it. From this experience, I have to be very very sure what I want. No more impulse buys.
I guess if your store is cool about reselling, there is no harm buying any bag that you've been offered, use it and decide if it's for keeps. But if your store is sensitive to reselling, you'll then be walking on eggshells. Because someone might just tell on you.