My case was when a man came to my house and spend a night there. They just assumed I slept with him. I was already in list of "not good citizens", they had no info on me ever dating a woman, I was a loner and not "a man of collective", and I was already in re-educational camp during my school years for refusing communist ideas, so I was under suspicion. They were not able to find any evidence and I was only 18, so I only served 6 months of unpaid labour (and then sent to obligatory military). Next time they promised to put me in prison for years, if they suspect me sleeping with a man or doing any other anti-communist actions. However, it never happened, as USSR crashed and burned.

Interesting enough that female homosexuality was considered as "sexopathology" and was forced to be cured. Mostly by sending them to spychiatric asylums or making surgeries. Treatment was either with electroshocking women, or transing them into transmen with testosterone and surgeries. Homosexual men who were in prison few times for homosexuality were sending there too, and transing them into transwomen with obligatory surgeries. While male homosexuality was leading to either prison up to three years (or to 5, with special circumstances) or long unpaid labour. And "must be catch up doing it" is BS, as it was just assumed that you have sex (for obvious reasons - you are homosexual and live together) and that's it. If sentence was more than 1 year, than there was just doctors expertise, they were checking anus for "micro-tears" or for sperm signs.

In general homosexuality was seen as "moral degradation of lazy people, and capitalistic propaganda". It was believed that homosexuality just randomly appeared in lazy or greedy people, or in people who had too much heterosexual sex and "got tired of it". So it was learned experience in their eyes, and because of that it was prosecuted - so it not spread on other people like a disease.