My friend's cousin told me that "everyone in Mexico has genital warts." She was exagerrating, but she is also a sex educator and was trying to put some fear into my friend and I . She also explained that condoms are not 100% effective against HPV because the warts may be in an area that is not covered. Also, there is no test available to see if you have the virus. The only way to find out is from an outbreak or the abnormal pap that women sometimes have. So unless you know the guy was lying, he may well not have known even if he was tested for "STDs." Be careful though and always use rubbers for many other reasons as well.
BTW, NIH (National Istitutes of Health) usually has the most up-to-date info on all kinds of health stuff.
http://www.niaid.nih.gov/factsheets/stdhpv.htm