Are you traveling for business or pleasure?

If you're traveling for business, are you using a corporate discount or booking through a corporate travel department/agency? You may be getting upgrades based on other business your company or travel agent is sending to the hotel.

Also, if you're traveling for business, do you include your company name and job title in the booking information/saved profile? If you're CEO or something else that might indicate you control/have sway over the travel budget, that might have an effect.

Finally, do you share a name with anyone famous?

All that said, sometimes upgrades happen for no reason having to do with you and everything having to do with the hotel.