I would be willing to bet the LFS owner was asking because walk-in-retail for LFS is the worst I have ever seen it, and he was trying to see what his customers would value more.
I live in an area where within a 90min drive there are quite a few good stores, whenever I go to any of them, there are rarely any customers and they are all trying to do whatever they can to spur business.
Without actual retail numbers to look at, it seems that most people appreciate cheaper prices, as the store in the lowest rent area, but the cheapest livestock is the busiest. The 'nicer', bigger, or cleaner stores aren't as busy, even if they offer a guarantee.
Knowledge of staff is also difficult for most customers to guage, as in the cheaper stores sound knowledgeable to most of their customers, but I see misidentified livestock, and a lack of understanding of basic reef chemistry, but most of there customers will never know it's incorrect. That advice seems just as good to most customers, as the advice from a different store that actual correct info is given.