Are acid traps real? (2014)
Are they real or not? 


These are general design guidelines that reduce the incidence of problems. However, today's PCB fabrication processes have improved to the point where good PCB fab lines can manage any trace angle that doesn't violate any of their other design rules, such as trace width.

Today's masks also provide substantial mechanical support to traces, so you can add some confidence that this won't happen to your design if you specify a mask.


  are they only real if you use a low-cost fab house that might use older processes?


I'm sure there are fab houses with processes that will have a slightly higher failure rate with sharp angled traces than otherwise.  It doesn't matter whether this is due to poor process, materials, or skills.