Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.

Is the word 'Customizable' a valid English word? Every time I write that word, the spell checker underlines it, and it suggests using 'Customization' or 'Customize'. I'm not a native English speaker, but that word exists in online dictionaries so I wonder why the spell checker underlines it.
The Oxford English Dictionary in its revision of March 2012 defines it as: That may be customized; able to be changed to suit the requirements of the user. Frequently with reference to computer software and hardware. The earliest citation is from 1960. If that definition of customizable suits your purpose, then there's no reason why you shouldn't use it.

If a possessive noun, which is plural, is preceded by 'each', then should it use the singular or plural possessive form? For example, which of the following is correct? spend time in each other's presence spend time in each others' presence.
Each other is singular, so the correct possessive is each other's. Edit: I found some controversy on this on the web because each other implies that there are multiple people involved, hence people think it is plural and should be written each others'. This, however, is wrong as each is always singular.

For example In Sim Lim Square cheat cases, a person paid $1k for iPhone insurance. He 'agreed' to buy it because the price was not clearly written. In some restaurants, prices are not written clearly and people can then be charged exorbitant prices. Insurance costs can vary by up to 100 times because the cost is simply not written clearly. Many politicians use deceptive language. Also, they tend to tell only the benefits without telling the negatives. Say you are a scientist. You have 10 studies supporting your theory and 90 studies showing you are wrong. You only quote the 10 studies to people that can't expect. All of these are deceptions that would make people choose really really 'bad deals'. Is there a word to describe such deceptions? Lying? Sophism? Fraud? Scam? Pull a fast one? What?.
Mislead/misleading One can be misled into thinking something, even if no lies are involved. Doesn't necessarily rule out lying though. The restaurant misled its customers by hiding information about extra charges