Question about spam

I don’t know how I got on all these mailing lists, but for the past several weeks, I’ve been getting spam about some “Banned CD that the government doesn’t want me to sell” and about how to get free cable. Now, I never do anything with these except to delete them. But I do wonder about something: in the subject line, there are always strange little phrases that have nothing to do with the subject of the spam. I probably get at least three of each of these things every day, and here are just a few of the phrases in the subject line:
“they would strike”
“I must have”
“I woke up and said”

So, why do the spammers put these off subject lines in? My WAG would be that it is to encourage you to open the damn thing if you don’t have a preview pane (I do have a preview pane), but there may be another reason. Input, please?

To encourage you to open the thing and also to get around any filters you may have set up.