Do you remember the Illinois Senate race where Alan Keyes got his a$$ handed to him by Barack Obama? Alan Keyes was in that race because Jack Ryan, the winner of the GOP Primary, dropped out due to a sex scandal where he tried to get his (ex)wife to perform public sex acts with him.
Jack Ryan was the candidate supported by the Club for Growth and the Whitehouse. His opponent in the GOP primary race was Jim Oberweis who is a good conservative. He was specifically opposed by the Whitehouse and the Club for Growth because he came out STRONGLY against illegal immigration. They were so opposed to him that they would not even back him as the candidate after Ryan dropped out even though he had run a fairly close second in the primary. He surely would have done better against Barack Obama than Alan Keyes.
When money gets funneled through the Club for Growth, you are providing the big business open borders lobby with a club that can be held over the heads of conservatives that might otherwise vote to secure our borders.
The Club for Growth often backs good candidates. I think their advice is worth listening too. Just don't funnel money through them. Give it to the candidates directly so they are free to vote like conservatives rather than as the bought and paid for tools of the open borders lobby.