Do objects used in food preparation and foods that have no or little chance of being not kosher really need a hechsher?
Please cite sources, if you can.
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Here is one agency's list of what doesn't need a hechsher http://www.star-k.org/cons-appr-no-need.htm
this is one answer about why some apparently hechsher free items might need a hechsher http://www.askmoses.com/en/article/144,2095417/Why-do-supervision-agencies-supervise-products-that-do-not-need-a-hechsher.html
this is about things that get into unsupervised food that don't appear on ingredients labels http://www.chabad.org/library/article_cdo/aid/529218/jewish/Do-packaged-frozen-vegetables-require-kosher-certification.htm
and this article also deals with actual problematic ingredients http://www.aish.com/jl/m/mm/Isnt_Water_Kosher.html
this one discusses relying on ingredients lists http://www.ok.org/Content.asp?ID=116
I know that the OU put out an article about processing and the mashgiach's familiarity with more than just superficial ingredients but I can't find it.
Rabbi Yitzchak Abadi, formerly a posek in Lakewood, and currently a Rosh Kollel in Jerusalem, as well as founder of http://www.kashrut.org/. He is of the opinion that Jews should continue in the ways of the Tanaiim in figuring out for themselves whether a food product is kosher or not. Hechsherim are mostly superfluous; it's sufficient to read the ingredients intelligently. He uses his authority to bravely declare that, for example, one may eat a tuna sandwich at any Subway chain, whether under kosher supervision or not, if one follows some simple guidelines. See here, here, and here. In fact, do yourself a favor and browse this website a bit. It's an eye opening experience for most frum Jews whose minds have been cluttered by too many kashruth organizations' acronyms.