Make arrangements with a REALTOR that you know and trust to represent your interests as a buyer. The REALTOR that you hire in advance will do a much better job for you than random calls to the listing agents of properties that you see for sale..
Also, the listing agent represents the seller and really cannot represent your interests when your interests conflict with those of the seller.
At best the listing agent can only be a dual agent representing both your inteests and the interests of the seller. Because the listing agent already represents the interests of the seller it is almost impossible for the listing agent to represent your interests when your interests conflict with the interests of the seller.
Once you have hired a REALTOR to represent your interests, then call the REALTOR who represents you with questions about properties that you have seen on Trulia. You will get much better answers that way.
Also, several of the agents who responded to your question are in Diamond Bar, where you are located.
I recommend that you call them first. Select one to represent your interests. The REALTOR that you select to represent you will do a great job for you, much better than anything that the listing agent can do for you. The REALTORS on here on Trulia are among the best agents to represent your interests that you will be able to find.
Real Estate Broker/REALTOR
Cell Phone: (408)509-6218
Email Address: firstname.lastname@example.org