Domesticated Animals

I wonder: if a fly enters a house, does that increases its chances of survival?  On the one hand, it will have access to food, and protection from the elements.  But on the other, it is now locked in an enclosed space with one or more large mammals that will try to kill it.

I'm wondering this because we could be breeding them one way or the other.  I've heard evolutionary biologists say that if a mutation helps a living thing survive even one in a thousand times, that will be enough for the mutation to become standard throughout the population.  So given the short life-cycle of insects, you'd think that by now, we would have caused them to evolve either an aversion or attraction to our houses.

It's disappointing that humanity has caused so little evolution in animals.  You'd think that:

• Squirrels would be more decisive, either running across the road or staying away, instead of going into the road and then becoming uncertain.
• Insects and spiders would become cuter, so we'd be less likely to squash them.  Though it occurs to me that this could go the other way: the scarier they look, the more likely we are to run out of the room and hope they go away on their own.