This is why I dislike Instant Forms! (Lead forms)
This particular client was spending an average of $3.90 per leads, and made $0! Yep, you read that right... they made $0! How? Well, the majority of their leads were lower quality. The commitment for a lead was minimal, and I am not a big fan of ads that don't need your customer to get off of facebook, as at that point they are committing their time to your offer. Unless you have a sales team to call up every lead and / or a system that helps you with the follow ups, I'd recommend staying away from it.