well I generally like the changes from Evony Age I to create a new gaming experience loosely based around the original Evony, it seems that the habits of those players have followed over to COE.
a really crappy tactic that seems to be all the rage is creating alt accounts to be used as place holders. these are not serious accounts that are actually played, they are just placed on the map near reds to reduce their production, and then all the free gems are used to bubble the city for a week at a time, whereupon a new alt is created (yet another lord.3212345 alt!) and teleported in with a new 7 day bubble.
to discourage this form of multi-accounting, my suggestion is that cities with bubbles up should not negatively impact the resource production of nearby cities.