Instead of buying the plug ins, we switched to buying candles to freshen up our home. One of the candles that we like is from Colonial Candle. We loved the pecan pie scent that when it burnt out, we went to the store to buy another one but it wasn't available anymore. However, I found a different scent and liked it too.
Although we love how the smell filled our whole home, it has one problem that we discover. At the end of the candle, it makes a very dark smoke and it darkened our walls and furniture. I cleaned our furniture and man, they were all black! So although we love the smell, we said bye bye to Colonial candle. For now, the Yankee candle works for us although it wasn't as good as the Colonial when it comes to smell but at least it doesn't cause black stain to our walls.