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We tested some models at Sundance and they just siphon water from tub to tub (scheduled in advance no deposit was required).
True, but a lot of water remains in the plumbing where you can't see it. If that water is not evacuated it'll trn nasty over time. After you left, spomeone had some work to do to fully drain that and clean it out.If the deposit is for wet testing a dry spa or to hold a sale price (very typical) that will be coming to an end and it's refundable then I would understand it.
"Prices good only for that day" smells of used car-ism. Perhaps not, but unless factory subsidies were ending that day, that price should be good until tomorrow or the next or next or....... It's a poor sales tactic in my opinion. If you have to bribe them for a price, what will you have to do to get service if needed? It would definitely put me off, especially if other dealers were not doing the same. I encounted no such attitude at my HS dealer and am not putting the HS spa down in any way.