If this was the case, wouldn't that give you the wrong impression to the interest level for your product?

I mean, how would differentiate the one that are seriously interested from the "others"?

It sounds like you're trying to trick more people into registering by hiding the niche from the people who aren't in it.

What will almost certainly happen instead is that fewer people will sign up overall. Especially for something like 'real estate', which is a well served market by a lot of B players, you need to entice people into signing up -- your best bet of that is to clearly identify the benefits to your target demographic.

There is no benefit in having 1 million people sign up that then realize the service "isn't for them". If you're charging for membership, then obviously that changes, but nobody is going to sign up for a pay service unless the benefits are clearly spelled out.