I'm doing work experience somewhere that organizes special offers for newspapers (no the newspapers pay someone else to organize them.) and I can tell you the following.

1) In 1 day alone for the competition in the News of the World "Who will be a Millionairre" we recieved 93.6kg worth of entries.
2) If you enter a special offer that uses tokens. No one bothers to check the tokens (well no one told me to bother)
3) In 1 day I've seen.
- Someone send an entire magazine because he couldn't find the tokens
- Several hundred people put stamps on envelopes for a freepost address (this is not a charity)
4) Do not send staples or paper clips through the post. We don't open them by hand. We have a machine which does it and it does this.
Duh Duh Duh Duh Duh Duh
Crack
Screech
*Turn off machine*
*Take out mangled paperclip/staple*
*Turn on machine*
Duh Duh Duh Duh Duh Duh

Please people be considerate.