Funny thing about STDs... no one ever admits to having them. And most people don't ever get tested.
Well, many STDs are asymptomatic. Or squeak by unnoticed. And are thus transmitted by people who have no idea they have an STD. Many of whom proudly proclaim they are clean.
Remember, many common STDs - chlamydia, gonnorhea, herpes - would make sexual activity undesirable or extremely uncomfortable to a person who is symptomatic.
So I have to laugh at the poll - knowing that statistically,
1 in 4 people have genital herpes (most people have no idea they have it)
Between 30 and 40 percent of the entire population, at present, will contract an STD in their lifetime. Not counting HPV, which is at rates upwards of 80%.
At present, 50 percent of sexually active people contract an STD by age 25
Around 80% of people living with chlamydia or gonorrhea have no idea they have it.
Sorry for no citations, but I'm recounting the statistics from memory for a public health presentation I did a few years back (and I can assure you my memory is quite good.)
I look at at this way - if you're under 30 and sexually active with people who have had more than one partner, you likely have something. Especially consider condoms don't protect against herpes, which can be asymptomatic yet actively shedding. And once in a committed relationship, face it - most people are quick to lose the condoms.
So to make my point clear, MOST STDs ARE TRANSMITTED BY PEOPLE WHO BELIEVE THEY DON'T HAVE AN STD... OR HAVE HAD A BASIC STD SCREENING THAT CAME BACK CLEAR.
Just my 2 cents.