Kashrut

Question

If you are in a place (say a foreign country) and you are reliably told that 99 percent of the bread from bakeries is fine to eat, can you rely on this, or must you personally check out each bakery. I ask because I have been reliably told by someone who knows the kashrut industry, that 99 percent of the so-called release agents that they put on pans so that the baked goods come off easier are made from mineral oil and thus kosher. Even if you say that the release agent is not batel (which it probably is) could you rely on the fact that use of non-kosher release agents are very rare, or is this something that would need to be determined in every case, and if not, why not?