Irritation.

It was 3am. I needed to pee. As you do, you're half asleep stumbling to the bathroom. I get into the bathroom and something sprays at me and scares the living crap out of me. It's my Mother's fucking 'sense and spray'.
I did not appreciate being scared out of my sleep by something so pansy-like.
She's got them planted all over the house. They are truly one of the most irritating things ever created by man.
What is wrong with good old fashioned canned air freshener? One or two are fine, in respectable places in the house. But every 30 minutes it's ready to sense and spray. You walk in to get something unrelated to having a crap and it's basically telling you "Oh hey, 30 minutes has passed and quite frankly, you smell of shit. Here have some vanilla compressed fragrance on the house."

I'm in the middle of a campaign to get rid of them. Watch this space...