When was the last time you peeked underneath your stove hood and checked out the exhaust fan filters? If it's been awhile or you've never done this, let me warn you: it's not going to be pretty. The purpose of a range hood filter is to collect grease, so if it's doing its job correctly, it's going to look and feel, well, greasy.
Over time the the filter may become so blocked with grease and ickiness that it loses its effectiveness, which is why it's important to clean these filters periodically. Thankfully, cleaning them isn't hard at all!