Can speakers sound worse during break-in period?

Hello,
Kenjit, Can you explain why a mechanical object breaking in cannot be measured. A woofer gets better excursion over time. It levels out at a point, but definitely changes. Since the driver is just a motor moving air to make sound the more efficient the motor becomes the more nuanced sound it can create. This is most notable at low volumes after the break in period. The same thing happens to a car engine. It actually gets better gas mileage after 5000 miles than it did at mile 100. If I am wrong please explain your comment so I can be educated. 

Break-in is  not only hoax , is some type vendor trick.If any customer
paid for example speakers he did not satisfy and planning to return The vendor say---wait, wait , after 100 hours break in sound will be much more better, and after  time, the guy  used to live and say, Speakers is not bad, sound much better, 

@hshifi.    better excursion over time and similar statement is the legend.   hoax

@hshifi 

Whether it can be measured is not the issue. The question is how significant is it if its audible? There are many more problems that can ruin the sound of a speaker and people that focus on things like cables and break in of drivers dont realize that. How about custom tuning the speakers with a bit of equalization? How about retuning the crossover? I tend to agree with what Harbeth wrote.

If you dont like what youre hearing its very unlikely that break in has anything to do with it. Has the OP bothered to retune the crossover to see how that sounds? If not, why not?

To have a guy that is clueless and argues almost every point under gods creation is one thing,  but to have a guy chime in that calls himself a manufacture that apparently has never taken the time to measure drivers at several points of break in is beyond my comprehension.  FS, QMS, QTS and even LE and RE all change as the motor and suspension break in.  It is threads like this that makes me back off of posting.