Well the grass taste is simply not having done a cure. I know if I don't flush for 3 days that General Hydroponics recommends my weed taste like crap. I know pop 22 would disagree he's got a great thread on all the scientific reasons why flushing isn't necessary, but if you can take a bud off a plant that's been flushed for 3 days and it tastes okay and then you take one off a plant that hasn't been flushed it taste like s***, well you might flush.