I had someone spoil the ending for me once. I was trying to read "Murder on the Orient Express" by Agatha Christie once and I had someone spoil the ending for me before I could finish it. I do hate it when someone spoils the ending of a book for me.
When I was in a college class, the teacher had us read a book called Feed by Mira Grant. It was alright, I liked it, liked it enough to continue it. Then, we all were talking about it and she more or less unloaded everything that happened in the followup books like it was no big deal. Never finished the series after that.
I've had people accidentally talk about something not realizing I was reading a book or had it on my to-do list for reading. & then there were sometimes I accidentally spoiled it for myself by doing a bit of research & some sites didn't have the Spoiler warning. Do I still read it? It depends. If it sounded good, I will read it because there's gaps in there & I want to know HOW the ending occurred.