Retrieve all Accounts if a users has Read Access to them using C#

private static bool retrieveReadAccess(IOrganizationService service, Guid userId, Guid avcId)
        {
            //retrieve user ReadAccess to account
            RetrievePrincipalAccessRequest principalAccessReq = new RetrievePrincipalAccessRequest
            {
                Principal = new EntityReference("systemuser", userId),
                Target = new EntityReference("account", avcId)
            };
            RetrievePrincipalAccessResponse principalAccessRes = (RetrievePrincipalAccessResponse)service.Execute(principalAccessReq);

            if (principalAccessRes.AccessRights.HasFlag(AccessRights.ReadAccess))
            {
                return true;
            }
            return false;
        }