This reminds me of fishing. I'm constantly trying to keep foreign scents off my lures (sunscreen, tobacco, gasoline, etc). Many other fishermen say I'm a fool because they don't worry about scent and still catch fish.
Are they right?
Unfortunately, we don't know how many fish rejected their lure because it smelled funky.
You grew decent plants with miracle grow. Great, but is that the best you can do? There's always room for improvement, and if you're really into quality, little things matter.
I'm not justifying what is sold in hydro stores, but some products really are worth the money.