Whether a dangerous or defective condition exists depends on the facts of each case, and is usually a question of fact for the jury. BUT: property owners will not be held liable for trivial defects, not constituting a trap or nuisance, that might cause someone to stumble, stub their toes, or trip.
A court will consider the width, depth, elevation, irregularity and appearance of the defect along with the time, place and circumstance of the incident. Photographs which fairly and accurately represent the accident site should be used to establish that a defect is trivial and not actionable. In Adler v. QPI-VIII, LLC, considered a photo that accurately depicted the step and the "clump" that allegedly caused a trip and fall. The evidence, and in particular the photographs, established that the alleged defect was trivial as a matter of law and did not possess the characteristics of a trap or nuisance, and, therefore, was not actionable.
Adler v. QPI-VIII, LLC (2d Dep't): http://www.nycourts.gov/reporter/3dseries/2015/2015_00320.htm