Do you think a hockey player uses the team owner's agent to negotiate his contract? Or course not....:)
When you use the Landlord's agent as your representative to rent space, that's exactly what you're doing.
In a Real Estate transaction EVERYONE is always looking after their own interests.
Never rely on advice from someone across the table from you. Always rely on the person sitting on your side of the table.
When you're renting a space, always make sure you have your own Broker. He/She doesn't cost you anything, and they are looking out for YOUR needs, not the Landlord's.