Or, you get 15% more from each unique visitor. Where "more" means more than your base street imagination per day. Let's try that again:
For each unique glitch that visited your street in a day, your street imagination stipend in increased by 15% of the base stipend - which, as you'll recall, is equal to your Qurazy Quoin value. By "unique" I mean to say that the same glitch visiting more than once in the same day doesn't increase the total.
The amount is rounded before being added. For example, at level 10 your base stipend is 55, and 15% of 55 is 8.25. If four people visit your street at level 10 you get 8.25 rounded to 8 times 4 = 32 extra imagination, not 8.25 times 4 = 33 imagination.
Animals will have to wait until early next week because it took me a couple of days just to sort this part out - in part because I had to level up one of my alts to verify my hypothesis. I do have a few animal results but I like to double check things before posting them. Machines will be even more complicated because there are four types of machines, multiple things you can makes with them and varying stack sizes to deal with, but, baby permitting, I will try to get some good conclusions over the weekend.