Problem when scaling 3d model

I'm just starting to use 3d and have exported my obj model from Blender. I guess it was rendered to a small size as it's barely visible, so I have looked at scaling it.

If I set the x / y / z scaling of the matrix to a positive number: it shrinks.

Is that normal?

Or does it taking a minus number to grow mean I've created the Blender model improperly? I'm not very familiar with 3d modelling, but is this a sign that the faces are pointing inwards?

I used a very old render program some time ago, and I recall that being an issue when transforming its models. Although there it would reverse the scaling, and so be apparent. In Blender my object scales normally, yet seems reversed when imported as an obj into GMS and scaled.
 
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