Here's something I'm ashamed to admit: Sometimes I purposefully go a different way (or I out-and-out hide) when I see people I know. Sometimes it's them in particular, meaning they're on my mental shit-list for some reason. Sometimes it's because I'm generally anti-social. (Oh, I can be pleasant enough in public, but I want near-total control over my time and my energy.)
Often I just don't have anything to say to people. Maybe the person is a talk-a-holic and I just do not have the time, interest, nor energy. Perhaps it is someone I personally despise. (It's a short list but still a list.)
No matter. I'm pretty good at avoiding common pleasantries when I'm in an uncommonly foul mood. I have been known to move parking spaces, turn and double-back in grocery store aisles, and attempt to hide behind infant clothing displays.
I suppose it's all good in the end, though. If people happen to catch a glimpse of me as I disappear to avoid interaction, don't take it personally. It's most likely just me having an off day.
However, and this is a HUGE PIECE OF ADVICE: If you know you've pissed me off or lied to me lately, and I do NOT avoid the confrontation, this means I'm probably going to unload whoop-ass on you ... and you inevitably deserve it.
There. You've be forewarned.