Yeah, when you walk up to the board just use the option to write your own notice. Visitors in dreams can view the bulletins as well, so all you have to do is put one up, create the address, and remove it once that's done. Alternatively you can just leave it up (so you don't have to re-do it every time you update) and specify it's for dream visitors only. And honestly, people in general can be overly critical, and even more so on the internet. At the end of the day, it's your town, and your dream address, so you don't have to share it, and anybody who ends up there randomly because they have no friends addresses to visit are the last people whose criticisms I would listen to--anyways, they won't even know who you are so it's not like they'd be able to say anything directly to you! Tbh, some people would find something to complain about even if you had uncommon villagers and had poured hundreds of hours into creating a unique theme with custom patterns and everything #forgetthehaters XD