If I need a mental health day, for example, I may call into the sick-line, and say I'm physically ill.
Don't do that. Just call in sick. Don't tell them what kind. However, don't then do things that are inconsistent with being sick.
If you can see a mental health day coming, then arrange for a personal day and do whatever you want.
Or, work overtime for a bit and then take a flex-day with a clear conscience.
I may do social lies: "I can't come to your party because ___ (lie.)"
Don't do that. Just say, "Unfortunately, I can't come to your party". Don't make up excuses. Just give the information. If you want to go to the party, then follow up with "Please ask me again. This is just unfortunate timing for this one instance." If you never want to go to a party thrown by this person, then keep saying no.
I'm against googling candidates because I think the informal sphere (public or not) shouldn't figure in hiring decisions.
I, on the other hand, think that how people present themselves in the public sphere is important to some kinds of hiring. I respect someone who is discreet enough to use a pseudonym for some purposes. I respect people who can decide what ought not to be public. People who aren't smart enough or discreet enough to use pseudonyms and then put private things in the public eye, knowing full well that they are in the public eye aren't the kinds of people who I want to hire.
People who scrounge to figure out pseudonyms and then feel a need to make them public reflect poorly on the scroungers, not the person being revealed. People who make private things public without permission also reflect much worse on the revealer than the exposed. For example, I think Weiner should have said, "Yes, that was a private thing that was leaked. Moving on..." instead of trying to cover it up. He lost my respect for being a weaselly bad liar, not for taking pictures and sharing them.
Likewise the people who went to Madison to protest should have owned their protest instead of getting fake doctor's notes. I respect someone who will stand up for ideals (even if I don't share those ideals). I don't respect people who weasel while claiming it's for the greater good.