Conservatism and being suspicious

"Being conservative" is the hallmark of a value investor. Which means, always look at companys with a suspicious eye. To illustrate -
a) I have come across a number of companies which always account for only a trifle of thier PBT for purposes of taxation. (called tax charge in the P&L account). Corporate income tax in India is 33%. Yet they create a provision for only 5% or even lesser amount. This would be incorrect unless they have a tax holiday.
b) Any inconsistent change in value of sales/profits should be looked at negatively. Why was there such a marked change? What did the company do to get such a change? Be doubly suspicious if the number is reducing.
c) Always be wary of "non recurring" income or expediture in the profit and loss statement
d) Sales/profits are not growing - be suspicious. (these companies are negative companies for us)

The idea is not to pick negative points in scrips but to do a perfect evaluation of the stock. I have found myself, when is the going is smooth, to actually start picking "uncalled for" good points in even some bad stocks. I have lost a good amount of my gains due to this. Be careful of such tendencies. As Warren Buffett says - "its better to be approximately right than being precisely wrong"