If you see answers, which are clearly links to spam or malware, why can't you report more than 5?

Actually, what you may be thinking of is the 'report 6' concept. While I don't know that it has been verified as 'official' by staff, the rumor is that when reporting spam, you should report 6 of the postings. That many reports ends up sending an alert to the staff so they review the entire account. If they find out it is a spammer / malware, they will strip all postings and suspend the account. The report 5 limit, then, might be to STOP at 5 reports so an alert is NOT sent to staff. But since you DO want this person investigated, you should report 6 in the future. And again, all this is speculation as far as I know, so even 5 may trigger an alert.

Now, moving on to another issue. Spam vs. Malware. If you truly suspect that the links being posted are Malware (not just spam), check out this link to the Suggestion Board. This is meant to be used ONLY for posting reports of malware on Yahoo Answers (and other issues on the Suggestion Board) so staff are immediately alerted and can strip the account. Do NOT use this for simple spam reporting, however. And thanks for trying to keep this site safe.

As far as I know there is no limit to reporting abuse unless this is a new rule I have never heard of.

Being a trusted reporter is part of being a good member of Y!A.

You can also have your contacts and fans report an abusive answer also since it take 2 trusted member to report spam, malware or anything else that is against the guidelines.