It depends on your relationship with your manager/company but gotta do it sometimes. It's a give and take.
There have been plenty of days i was supposed to work and I stayed home..with pay... no PTO used. So if one day they need me to take over an issue/outage for the oncall person i have no problem with it. I'll probably take a comp day for it anyway. That was at my old job where we had X amount of PTO and shyt.
My current job we get unlimited PTO and I must say while i dont abuse it, i do use it and work from home often. Almost once a week and sometimes twice. I cant front there have been days when i worked from home and didnt have a whole lot to do or caught up on all my work so i spent the whole day either in bed or out and about chilling. I just keep my work phone on and logged in on Skype in case something came up.
So a job like that if they call me on my day off and be like
"yo we have an issue and so&so isnt available. Can you take care of this?" I have no problem doing it. We molk the cow but gotta feed it to keep it alive sometimes.