Sexing How do you trust the sex of a pig when adopting (not from a breeder/store)?

Just curious, I've never adopted a pig from someone else's house before, and whilst I'm not looking to get any new pigs right at this moment (just had a trauma of some of my pigs dying), I am interested how people go about it.

I saw a single female pig for adoption really close to my house, I showed her to my husband and he asked 'how would you know if it's a girl?' - if there were two of them, I'd believe they were probably two girls, and not both been males wrongly identified, but with one, well I wouldn't know how to be 100% sure.

I haven't visited someone else's house to view a pet before, I don't think I'd just go and pick their pig up in my hands and look at its bits. I'd just think 'hmmm really no idea what it is!' and I'd say 'OK I'll take her!'. I suggested to my husband that we could adopt a single one and put a divider between them, if it's a male pig he'd be excited for my two females - but then I'd be stuck with a male pig.

Just curious, there's many single pigs always up for adoption near me, I think when I look to get one, I may consider adopting one lonely pig, but honestly, I don't know how to trust the gender!! Most listings are from just usual pig owners, the kids are grown up, they're moving house, they've bought a cat etc - NOT breeders. So it would just be trusting the advice they would have been given at the store where they bought the pig - and whilst I know what guinea bits look like, I know in that scenario where I'd pick up an unfamiliar pig up to have a look, they'd be wriggling around and I'd have no idea what bits they have!!