Stock prices go up, and stock prices go down. Tell me you found a stock that always goes in one direction, without even the slightest bump along the way, and I'll politely decline buying that cool bridge you have for sale. It just doesn't work that way. But in the long run, good businesses almost inevitably deliver strong stock returns while the lesser lights fade out.Wall Street is always a bumpy road, and the temporary downticks for potential long-term winners can be great buy-in opportunities. That's wha ...