In a statement issued this week, the regulator provided top tips for the public on how to deal with requests for cash from fundraisers in pubs and restaurants.
A commission statement read: "We all feel more generous during the festive season, but unfortunately there will always be some people who take advantage of this generosity to line their own pockets at the expense of charities."
Drinkers should be wary of people who say they are collecting for "sick kids" or "the homeless at Christmas" without naming specific charities, the commission advised. It also encouraged people to ask fundraisers if they have written statements from the organisations they claim to represent.
The regulator sent a similar warning to pub owners, who were advised to help stop their customers being "cheated".