Ultimately what would work best is transparency.
As suggested in the blog entry key figures should be disclosed. eg
• total income (donations etc)
• operating expenses
• disbursements to the charities/programmes marketed
•ratio of above

The only issue is it's not always clear-cut in terms of disbursements to the charities marketed. eg. the Blind Foundation may have a staff member who handles admin AND directly provides a service to the blind.

In terms of fundraising for overseas activities, the charity here may send 90% of funds collected because they want to maximise the ratio of funds disbursed, but without effective auditing, the overseas counterpart may be squandering some of the cash. In some instances a lower ratio of funds disbursed works out to be more effective as additional checks/audits would minimise risk.