I had bed bugs for the last month in my last apartment. No idea where they came from, but it was awful. I used spray bottles, store-bought foggers, sprayed raid all over, washed sheets every couple days. It didn't do anything to hold them back. There were nights where I couldn't bring myself to sleep, like I could feel them crawling all over. It was like psychological torture. The bites themselves weren't nearly as bad as that (though they still itched like crazy). Some people have hired professional exterminators, tried moving, thrown out their whole bedrooms and still can't shake those [censored]ers.
Thankfully, I've managed to avoid carrying any with me to my new place.