>>4236724The overexposure is meant to combat fogging of expired film by brute-forcing an image onto an already hazy negative. It (generally) looks like shit, colours get fucked up, monochrome images look like picrel with extremely blown highlights and very little shadow detail.
Use an expired roll which you are unsure of storing conditions as a play-roll, expect nothing and you might be pleasantly surprised.
About heat. Heat can absolutely destroy film as it makes it age faster, hue shifts, fogging, all that stuff. It certainly is better than wet and warm.
As a kid I was given a 110 instamatic camera to shoot over a summer, I ended up hanging on a nail under the eave of a roof and promptly forgetting about it like children do, and I found it some 4-5 years later, finished the roll, then waited another 10 years to develop it and incredibly enough, I actually got (terrible) pictures out of it despite the extremely wet and warm conditions of multiple summers.
tl;dr expired film is really unpredictable and is a complete crapshoot, store your film right for predictable results
