Thirty-five per cent of respondents to the poll, carried out by CCBFastmap, said they had stopped giving to a specific charity at some point.
Of those, 22 per cent said they had stopped supporting a charity because it was not clear how their money was being spent.
Forty-one per cent stopped giving simply because they could not afford it.
Nearly 70 per cent of respondents said they currently donated to charity. Six per cent were happy to receive phone calls and 20 per cent were willing to receive direct mail packs.
High administration costs, high directors' salaries and bad media publicity also made it onto the list of reasons why donors lose trust in a charity. However, none of the donors had been tempted to change allegiance because of incentives or free gifts.
Contact by mobile phone came out as the least popular means of communication.
CCBFastmap questioned 4,000 UK adults for the poll as part of its Marketing GAP Tracking Study, which it has run annually since 2005.