i washed out a lemonade bottle to do nothing more than bring the water from my sink to my grow area. i washed it for like 25 min until I could barely smell lemon. The water i used was in this container for no more than an hour and it plummeted my soil ph. The runoff went from 6.5 to below 4 in 1 watering. very bad news. and not to be a douche but how will soap possibly improve the taste or smell of weed? i once had some weed a friend grew that tasted and smelled like laundry soap. no one knew why but it was not pleasent. we got high but it was no fun to smoke. if you want the bud to have a certain taste or smell you need to use specific seeds. if you want to enhnce what is already there stay away from too many chemical ferts, feed molassess during flower, and flush (although i cannot personally vouch for the validity of the flushing theory most good growers agree that it is a good idea).