A bad customer is something like a bad employee. They both cause friction (requiring extra energy for the most day-to-day pedestrian of company activities).<p>There is a simple observation (among many) one can make to determine if a customer is noisy/bad/a distraction: "Does this customer (new or old) engender scope creep on the main company product or make demands of the workforce to such a degree that it diminishes the attention available to keep existing customers happy?"<p>Quite often, especially in a subscription-based model, where there is monthly or annual recurring revenue, the damage done to the business will not be noticed until the existing customers are screaming or walking, by which time it is too late to catch up.<p>There can also be the temptation to go after new customers by expanding or changing the product line, and quite often this is a condition of securing the new customers' business. This can be seen as the route to the "big time", however one must always remember that without the small-time, there is never going to be a "big time".<p>In short, prevention is better than cure. You wouldn't hire a toxic employee. Don't bite off more than you can chew by taking on a demanding customer whose needs don't match your services.