I think it depends on the product/idea. If you have gone straight to "renting out spare rooms" then you are also going straight to the sale rather than the mark

I think it depends on the product/idea. If you have gone straight to "renting out spare rooms" then you are also going straight to the sale rather than the marketing. If you are instead thinking like "I'd love to do something with electric cars", you are more likely to pitch expertise and possibly something less specific to try and feel for where the real value might be. Plenty of people already know a gap in the market and plenty of others think that just because they like their idea, a market will magically appear. I have worked for both.