What do Adcomms look for in a LOR?

[Ankghost0912]

Hi,

I have applied to MIT for this fall and was wondering how does the adcomm see the LOR. I mean are they just like product endorsements or more like a probe into applicants abilities? Also, does it really cast a bad impression if the professor writes all positive things about you and are things you do in a class really matter? (like asking probing questions, solving problems and helping others etc)