YMMV, but I've experienced lots of this in my current role (engineering manager at tech support in $EngineeringCompany.) Customers keep asking for info on upgr

YMMV, but I've experienced lots of this in my current role (engineering manager at tech support in $EngineeringCompany.) Customers keep asking for info on upgrades, specs, try to trick us into doing detailed engineering - then suddenly boom, they are dead quiet at best or at worst stalling - replying to your requests, but only non-committing. I've since made it a checklist item that we notify our customers right away during first contact that IF they lose interest for any reason whatsoever - just let us know so that we may put the matter to rest, no hard feelings. Stalling until we give up is not kinder than just being brutally honest. I've found that quite a few customers appreciate us stating it so bluntly, as it gives them, too, an easy way out of the otherwise awkward situation of us spending time and effort providing solutions (or gathering a response!) and them from spending same trying to let the matter drop without expressly stating they are doing so. It does not prevent us from spending time on projects which never come to fruition, but it does help us cut our losses as the time between customer losing interest and us being able to close the matter is decreased.