There was a famous 24h florist in my city that everyone joked had to be a front for something. (Turned out it was drugs.)

Coincidentally, there's a shop in my neighbourhood that's also floral-themed and suspicious as heck: it says it sells flowers, but I only see potted plants (that don't appear to be for sale) and earrings on display stands (which do appear to maybe be for sale) when I peek in the window. I've lived here for many years, and I've never once seen it open, no matter what time of day or day of the week I walk past. With rent constantly rising and quite a lot of businesses in the street closing or moving away, it seems highly suspicious that this one could be turning a profit without ever being open.