It’s actually very natural for breloom to spray spores, so it’s not exactly something to worry about. That is to say, your breloom is perfectly healthy; it’s simply that she’s responding to environmental issues.
Specifically, there are two reasons why a breloom may spray spores. The first and, to be honest, less likely reason is because she’s feeling threatened or stressed. If you’ve recently moved, if you’ve obtained a new pokémon, or if there is a bit of activity around your neighborhood (such as a construction project), your breloom may be attempting to comfort herself by spraying poisonous spores as a means of self-defense against the perceived threat. If you notice a slight purple sheen to your breloom’s spores, then this might be the case, and it’s important to calm her down and explain to her that she’s perfectly safe.
However, if this has always happened, if you’re finding it all along your baseboards, and if you don’t detect a purple sheen, then this may also be her way of marking her territory. In their native forests, breloom outline their territory with a boundary of spores. This boundary serves as a warning; to other pokémon, it means that beyond that line, there is a breloom ready to fight. So every time you clean those spores up, you’re basically erasing your breloom’s territorial boundaries, which in turn may be confusing her. To counter this, try to explain to her that the walls are territorial boundaries enough. If she doesn’t quite understand and still sprays spores, try to strike a compromise with her. Assign her a room (even a closet will do) that’s completely hers and tell her that she may only spray her spores there, as that is her only territory in the house. The rest of the house is your territory, and thus, you don’t appreciate having her mark every wall in your home. Reinforce either idea positively: give her treats, either for every day she doesn’t spray (for a few weeks, anyway) or for going into her designated space to spray whenever she feels the need.
The Pokédex According to Bill 