One way to spot hidden potential is to gauge someone’s enthusiasm for your ministry by the amount of effort they put into getting involved. Consider Zacchaeus (Luke 19:1-10).
To be sure he could watch and hear Jesus, Zacchaeus ran ahead of the crowd and climbed up a tree. When Jesus called out to him, he immediately responded and promised to turn his life in a godly direction. When someone says they are interested in your team / group / ministry, watch to see if their effort to get engaged matches their words.