Your hydrangeas look perfectly fine.......I see no black spots.

Look at the last pic more visible on that

If you mean the minute spotting on some of the sepals, that is most likely due to irrigation or rain or other weather conditions. Very common on many white flowered plants (more noticeable) and harmless.

Beenadee. No one's mentioned it, but it looks awfully close to the side of a property.

I agree with Alan that it looks close to the building. It is supposed to reach something like 9’ tall and wide, which means that it should be at least 5’ from the side of the building so there isn’t constant damp foliage against the building. It will also look better if it isn’t squashed against the wall.