First off, a few formatting issues. Item #, Special Containment Procedures, Object Class, Description and Addendums should all be bolded. Also, use "SCP-XXXX" instead of "SCP-goo". I know that "goo" isn't its number, but XXXX is easier to read than "goo".
contained in a padlocked safe
I imagine the Foundation would make a better lock than a padlock. And for an item such as this, a secure locker would work just as well.
Testing is to be only done by D-Class
The way this is worded, it makes it look like only D-Class can do anything with the SCP, meaning that all the experienced researchers can't test. Perhaps add a necessary Level for personnel to test.
7x8
7x8 what? Meters? You need measurements here.
Testing Chamber 225
What happens if Testing Chamber 225 is damaged or not available? It's best not to put specific rooms or personnel.
Incident goo-01
This Incident isn't in the article, unless the Addendum is supposed to be the Incident Report, in which it would be labeled "Incident goo-01".
stereotypical red1 using musical instruments
"stereotypical red"? What does that mean? I'm guessing this was a typo.
Effects:
Effects aren't a separate part, they're put into the Description.
Addendum: During testing SCP-goo-1 suddenly played a song different from any other song listen on the album.
Is this the Incident reported before? And SCP-goo-1? What's that? What song was different?
