Property Walkthrough Prior to Offer?

[KC Jones]

Good afternoon Bigger Pockets forum! I am a new investor and this is my first post to the forums here!! I am currently facing an issue that I would like to get experienced investors opinion on to see if my thoughts are warrented or not.

I have started doing a lot of searching for my first deal and have come across a property I really like. I recently asked to schedule a walk through of the property prior to submitting an offer. The property is almost 40 years old so there are certain items I want to see prior to going in on it. I was told that I cannot do a walk through until an offer is submitted and accepted. I was also told by the realtor that the tenants do not know the property is for sale and to not try and get in touch with them about it. Is this a common practice (the realtor trying to weed out anything but serious buyers), or something that is a bit out of the ordinary. My initial thoughts are along the lines of the realtor and/or buyer trying to keep certain things hidden.

Thank you in advance for any help and opinions that you can offer!!!