A study has been released detailing which words spammers most like to hide, with 'Cialis' coming out on top. The report, by anti-virus company Sophos, highlights erectile dysfunction drugs, mortages and porn are still spammers weapons of choice.

The most popular word is 'Cialis' a Viagra-esque wonderdrug, followed closely by 'orgasms', 'Viagra' and 'shipping'.

With drugs taking up much of the top ten it's clear where spammers make their revenue, but the report also reveals the ways in which spammers try to make sure their mail gets through.

"Spammers have a dilemma," said Graham Cluley, senior technology consultant for Sophos. "They want to sell certain products or include certain phrases in their spam emails, but they also know that many people will have filters looking for those words and automatically junking them. For this reason they use obfuscation to try and disguise the words from the anti-spam software."

Obfuscation is the trick of slightly altering a word but not disguising it so much it becomes illegible.

According to Sophos up to 80 per cent of spam uses obfuscation, even though most anti-spam filters now employ sophisticated algorithms to weed out spam.

The top ten (and other interesting entries)

1) Cialis
2) Orgasms
3) Viagra
4) Shipping
5) Milf
6) Valium
7) Pharmacy
8) Xanax
9) Increase
10) Vicodin
40) Windows XP
138) Replica watches
226) Naughty
258) Cheerleaders

www.sophos.com