PMF... Your new neighbor has an unencrypted WiFi signal with no log-in showing on your drop down list of local internet WiFi providers. Did she forget to turn on encryption or is she just technically retarded to figure it out? She could be ignorant of how to turn on encryption, but it may be something else.
1 Is this open WiFi signal a "honey pot" to grab credit card data?
2. Maybe it is a police sting to catch data theft?
3. Is it a counter-intelligence operation to monitor internet activity of a suspected intel agent?
4. Are you under official observation and WiFi is bait to get something on you?
The tactics used in foreign countries to monitor suspected intelligence operations are now routine in Western countries. It's always a good idea to never use your real name or address when online unless you KNOW FOR CERTAIN the encryption is turned on and even then, you may have government monitoring every keystroke anyway.
One possible indication that the open WiFi invitation is government-supplied is that the WiFi identification will have some name attached, like "John's Imac" or "Mary's MacBook" to give it the appearance of being a casual mistake or simple-minded WiFi user. They want you to think it is a sloppy user and you're lucky to find a free WiFi internet connection at someone else's expense.
At the very least, they could arrest you for data theft, or theft of IP services, if it happens to be the FBI or police who set up the open WiFi connection. At worst, they could be looking for a spy using what he thinks is someone else's WiFi to transfer classified information.
If the open WiFi stays that way despite you using many megabytes of data or even gigabytes, without ever being encrypted, that is another red flag that it may be a covert bait trap and government operation.