Not-for-profit think tank nfpSynergy asked 1,000 people what they found "off-putting, worrying or irritating" about charities, offering them a list of potential concerns.
Sixty-one per cent said they were worried about how much of the money actually went on the cause. Fifty-one per cent said they were concerned about how much charities spent on administration.
Joe Saxton, co-founder of nfpSynergy, said charities were not doing enough to reassure people their money was well spent. "Donors need to be constantly reassured about how much goes on fundraising and administration," he said. "But we also need to make the argument that there is good reason why we need to spend that money on those areas."
The survey also showed that 45 per cent of respondents were annoyed at receiving phone calls at home and nearly 40 per cent were irritated by door-to-door collections and the amount spent on staff salaries.
A quarter were put off by collection envelopes through the post, 22 per cent by direct mail and less than 20 per cent by face-to-face fundraising. Charities campaigning for change put off only 3 per cent of respondents.
Richard Marsh, director of the ImpACT Coalition, which promotes transparency by charities, said organisations should not feel let off the hook by the figures on fundraising activities.
"There is still massive concern out there about fundraising techniques," he said. "People do find some of them opaque and annoying. Charities need to be more proactive in explaining how it is they do their work and why they choose the mix of techniques they do."
The same survey showed the public overestimated the proportion of income charities spent on administration. Most guessed charities spent about 40 per cent of their fundraised income; the actual level is 12 per cent (23 October, page 1).
WHAT PUTS DONORS OFF ...
61% How much really goes to the cause
51% Amount spent on administration
45% Telephone calls at home
39% Door to door collections
39% Amount spent on staff salaries
25% Collection envelopes
22% Direct mail appeals
3% Campaigning for change