I have seen so many small businesses fail because they had stupid ideas or located in unsuitable places
Spot on. Time and time again, I've seen (in Poland) people open a business that they had a dream of running, rather than one that there's a market for. Often ones that are doomed from the start due to competition etc.
A friend opened a hearing aid shop in a small town in south/central Poland. There were two there all ready. It lasted a year, and in that time he had zero customers. Not one single person came through the door.
Somebody else I know had an idea (and the life savings) to open a pizza restaurant/takeaway. The kind of idea where he'd chosen the name and the design for the pizza boxes before he'd found premises. He found somewhere surrounded by student accommodation and not much else. Sounds great? No. He was almost offended when I said he could do extra cheap ones, 'student specials' etc. He wanted it to be expensive and upmarket. You can guess the rest.
Another person I slightly knew bought a moribund pet shop, in a low density, almost semi-rural, area, walking distance from a 'pet superstore'. He ended up hanging himself in the shop.
What about (and this would work best in a high density residential area on a main road) a 'barrel grocer', one of those places where there are big tubs etc of various dry goods, wahing powders, pet foods, powdered foods etc and people can weigh small or large quantities out and buy them by weight. You'd need to give out those plastic gloves that supermarkets have in the bread section due to Sanepid rules, or even weigh out and seal a lot of bags of different amounts first. This would work best in a poorer area - there are lots of shopping precincts with empty premises around, and once the place is known about, could have very steady custom.