I fill my shop up with customize furniture and let the villagers pick and choose. I have noticed that my villagers houses are getting filled up with bugs and fish because their favors usually involve me catching them an animal...
If you want to keep your villagers homes original or not looking like some kind of warehouse, it's easier to book all of the spots in Retail and jack the prices to unreasonable amounts of bells. I have everything booked at 999,999 bells...or whatever the limit is.
I used to not do that and didn't care what my villagers bought or sold. Then some of the cooler furniture started to be sold at Retail and the villagers always kept their uglier pieces. Or they replaced their awesome furniture with junk from Retail. So they'd have a house befitting of a clothes store or something.
It just made it look ugly and illogical. So I booked all those spots. Now I don't even do any requests for them that will replace stuff in their house. No fish or bug requests, furniture, ect...
One of my jocks still to this day has an unfinished fossil piece in their house. It's so ugly. I think I tried to buy it from them when I visited once, but they refused. So if they ever need furniture to replace the fossil, that's the only time I'm going to make an exception.
