My parents internet sucks. Download speed is like 40kb/sec, and I found this internet that is being given off by someone near my house. 200kb/sec internet. It's unsecure. Is it bad if I leech it? BF3 might finish download this week! (Joke)
Technically i think it is illegal. but no one ever does shit about it.
If they really cared, internet cafes would be just cafes, and no one would sit in Starbucks.
But it's not an internet cafe, it's someone's home internet, probably old people, left unsecured. Glad it's not enforced. It's so much faster than mine!
I wouldn't call it stealing if its there for use, I call it using.
If you're that concerned about it and you know who's internet it is, ask them if you can use it.
You're using it without their approval/permission/knowledge, aka stealing.
Simple.
I'm not saying you should or shouldn't use it. If it's there, go for it. I'm just answering the OP.
There's usually a spot in the user agreement that says you're not supposed to share your internet with anyone outside your home. If anyone's caught using it, such as one in your position, you can get arrested depending on what your local laws are, but that just comes down to where you live.