Should we sell stocks during slow down?

When you feel the market is at it's peak whether a slow down is expected or efficient prices are reached(there are objections to this from finance theorists) one can sell tantamounting to a short sale with the hope that one can purchase them back at lower prices later.

But the problem is identifying the peak. Modern theories feel during expansionary pahse of the economy one cannot predict the exact peak ie; the efficient prices will be rising. Warren Buffet never buy stocks to sell, he buys to own them for ever but he does so after very conservative analysis of the stock before buying. He has something called filters which include a company that has it's working capital growing for the past 15 years, it paying dividends regularly for the past 15 years, has high stabiity meaning good equity base, value ie; market price not more than 18% of book value etc;. Like this there are around 15 criterea which he uses as a filter and if the stocks meet this criteria then he buys them. In fact he even buys companies ourright if they meet this criterea. One can contact him if someone has a company which meets his criterion. He owns around 350 companies that meet his stipulations. He never sells them afterwards.

one has to see the sensex and study for many past months for the particular share ,if trend is downwards continuously then in this bulish market selling will be better,but if fluctuating i.e.sometimes up lesser time low,then has to wait and watch for some time.

I think you need to reframe the question well !!!!!!!!