Question anything that seems suspicious. 

Deferred maintenance is a little harder to quantify but if you get a T12 (trailing 12 months of income and expenses) you can see if expenses look suspicious low.

@Tony Karns I would be very suspicious of a duplex listed on the market at $360k where market rents would be 1% or more.

You don't even really need the appraisal until the approval comes in if you're suspicious.

One potential lender has attractive terms (8%, 2 points, 100% financed, no prepay penalty), but on the phone he has very spotty English so it's hard to talk to him, and his contract seems suspicious in areas too.

@Nathan Asher Robson well something like 10 Americans have died there recently under suspicious circumstances, likely do to illegal (read poisonous) alcohol.

This seemed too easy to me, but I wouldn't want to miss out on a great opportunity just because it sounds suspicious. 

Yes I was a little suspicious of Thumbtack which is why I started asking around and was looking at Google and Yelp reviews. 

I've been bombarded with flipster software messages to my email since yesterday and I'm growing suspicious.

I would be extremely suspicious of these kinds of replies.