This is an outlet at my in-laws’ house which was built in the 1960s. I’m not sure if this is just some paint that was put on an outlet and has worn off over time or if this is some residual evidence of sparking/minor electrical fire. The walls are wood panels painted white, so it seems to me someone might’ve just thought they could paint the outlets as well (there are some parts of this basement that don’t have the wood painted and the outlets/switches are dark brown, which might be what I’m seeing). The outlet seems to work but I don’t feel totally comfortable plugging something more expensive like my laptop in, even though I suppose the charger would be more likely to die than the actual computer. The house has a fairly new electrical panel with breakers that seem nice, but it was also built initially as a duplex (with a later addition making it useable as a triplex) and each part has its own old sub-panel that still uses twist-in fuses. I’m still not sure if whoever put in the new panel said the rest of the wiring/outlets was fine or my father-in-law just decided upgrading the rest was too expensive.
If this is the only receptacle in the house that is causing some unease, then it’s simple and cheap enough to replace the receptacle. Around me, the cheapest UL-listed duplex receptacle at the home improvement store is less than $3. For the “commercial-grade” receptacle with my preferred backwire terminations, about $6. For TR-rating, $8 out the door.
Someone that’s handy (and careful) with electricity should be able to swap it out in 20 minutes, and then you won’t have to worry. Of course, as with all home improvement, don’t do it yourself unless you’re reasonably confident. And opening the outlet box might reveal new issues. But there’s only one way to find out for sure.
I think there’s another one in the room that looks basically the same, but again, probably just paint. Normally I’m perfectly comfortable swapping out an outlet or light switch, but those have all been newer houses with breakers and copper wiring. I think this house was built in 1966, maybe 1962, and I have no idea what the wiring standards in Quebec required at that time. I might try looking at it more on this visit, though.