As Peter said, Paint will stick if prepped and applied properly.
I would recommend only applying paint to large flat surfaces and avoid painting any "edges" that will receive wear like a rubrail, toerial, handrail, or where two surfaces meet like the edge of a cabin
Also, avoid painting anywhere a fastener or another piece of material (even aluminum) forms a crevice. A stainless steel
bolt mounted in unpainted aluminum will create a little white powder in the hole but otherwise not be a problem. If the aluminum is painted, that same bolt will likely cause corossion to get under the paint and spread well beyond the hole creating an ugly blister.
No paint means no paint blisters