Swallows are common birds in the south, and they are also close to people. They choose where to nest because they like it. As for whether it is good or not, this is a psychological effect, because some people have said that swallows will bring good luck when they come home to nest, believe it or not. Anyway, if swallows come to my house to make nests, I won't drive them away, but I will also put a few piles on the wall to help them make nests.