Supplements are no where NEAR placebo. There are idiots on one end of the spectrum that think they'll become and IFBB pro if they down enough creatine and fancy post workout carbs, then the other end of the spectrum completely disregards supplements all together. They do increase ergogenic performance but you have to appreciate them for what they're worth. It's not much, but it's far from placebo, especially if it's got a stim.
For the most part, they'll help you have an energetic and productive workout. They're not going to throw on slabs of muscle though. But if your diet's taking you in all the right places already, it will help.