Are 'touch up' paints any good?

[Duke]

As above really. I have a fairly long key scratch down the side of my car, the majority of it has been polished out, but there are sections that are deeper than others which wont polish out. When the cars wet after being cleaned you can hardly feel the scratch but when its dry it stands out like a sore thumb. Ive tried T-cut metallic and the T-cut that comes in a tube, both no good really.

Will a touch up stick cover the scratch completely or would you recommend avoiding them? Surely the paint wont lie completely smooth if you know what i mean and you will still see where its been touched up?

All help greatly appreciated, i want to try and avoid getting the scratch professionaly sprayed if i can help it!

Thanks

Duke