Amongst my real life friends when Pokemon was in its heyday, the myth went around school that Pokemon trained up using Rare Candies were substantially weaker than those who battled wild critters and such. Not knowing the inner mechanics of Pokemon Blue, and being a highly impressionable 10-year-old, I avoided Rare Candies completely for that game, and have rarely used them since. I know now about the basics of Rare Candies and their effects on stats, but I still use them very rarely. A small subconscious part of me thinks that they'll make my critters weaker or something. Old habits die hard, I guess.