if anyone wants to get this effect for the long run then follow my advice.
1. clean it wid glint or any gud glass cleaner.
2. after cleaning it thoroughly apply any good polish like armour all or formula1
3. after applying polish let the greasy texture remain for an hour, then clean it thouroghly wid a wet cloth.(coz all the oils have been absorbed by plastic by now and the grease on the surface is surplus, it isnt required)