Well, I know quite a few people who have had colposcopies and LLETZ treatment due to abnormal smears, and therefore I know quite a few people with an STI. I know even more people who had CIN 1 which cleared up by itself - doesn't stop it being most likely caused by HPV, as CIN indicates classic cell changes caused by HPV.
Funnily enough, I haven't known people be as free with their confessions about other STIs, so don't know anyone who's had any other infections... with the exception of one person that I know who did confess to having had gonorrhoea in her throat... I'm not sure enough people know you can actually get and pass on infections that way (even HPV, which has been linked to throat cancer...).