Looking at buy and holds that cashflow and are not in areas I need to take my conceal carry.

Is this possible in a unit with a concealed sprinkler system? 

Make sure you get your concealed carry license.......

Is this considered concealing of fact and the contract is voidable?

But concealing information to obtain a mortgage runs the risk of becoming a felony (multiple posts on BP about this) and I personally have no interest in that.

I have a concealed permit, so no one ever sees my weapon and luckily, I haven't had to use it.  

Is concealing your contact info common or is it usually a red flag?

Otherwise whoever you sell to if they get sick they could come back and sue later on etc.Anyone can sue but they might actually have a case for concealment if you knew of the mold yet tried to repair it cheaply and improperly which caused them to become ill.No legal advice given.     

Someone who is selling a dog will probably want to conceal as much as possible.

They have point of use options for low cost install or an in-line option, which may require a plumber to install, but they are more concealed and permanent.