All it does is lower your Evasion by one level and find wild Pokemon. You can just walk to find Pokemon in the wild because it's way faster. So, is it worth having?
Too put it in a word.............................No it is useless for competive play only ingame does it do anything semi useful
When trying to hit a higher frame, using Sweet Scent can be a very useful method, because it can advance the frame by a large amount; however, you must be very careful with your calculations. This method also does not require you to keep count of taps or flips and you can check your frame by checking the Pokemon you battle. No other method of advancement in DPP allows this.
source something you can read if you have no idea what the rest of this answer is saying