You have an instance variable used by few methods - reidev275/SignsYouShouldProbablyRefactor GitHub Wiki

Example

class CustomerManager
{
 ICustomerRepository _customerRepository;
 ICustomerBiller _biller;  

 void Create(Customer customer)
 {
   _customerRepository.Insert(customer);
 }

 void Update(Customer customer)
 {
   _customerRepository.Update(customer);
 }

 void BillCustomer(Customer customer)
 {
   _biller.Bill(customer.Id);
 }
}

Why is this bad?

1. The class in question could probably be broken into multiple classes to avoid a Single Responsibility Principle violation.
2. In this case BillCustomer probably shouldn't be part of this class at all.