As an STD assistant, I can clarify that dirty underwear with bacteria and fungi alone typically would not directly cause blisters associated with herpes. Herpes is primarily caused by the herpes simplex virus (HSV), which spreads through direct skin-to-skin contact during sexual activities or kissing.

While wearing unclean undergarments may increase the risk of bacterial or fungal infections in the genital area, these infections are different from herpes blisters. It's essential to maintain good hygiene practices to prevent various types of infections but remember that HSV transmission requires specific contact rather than just exposure to general dirtiness.

If you're experiencing blister-like sores on your genitals, it's crucial to consult a healthcare provider for proper evaluation and testing if necessary. They can provide accurate diagnosis and recommend appropriate treatment options based on your individual situation.