Floating spread makes different chart?

Since the default charts offered by MT4 brokers are based on bid line, wouldn't a floating spread make somehow a bit different chart than what the traders saw?

So, if the charts are different from 1 broker to the others, even in one account in the same broker can have slightly different bid-based chart from ask-based chart, wouldn't it make whole different candle pattern analysis?

Not really. Sometimes you can see slight differences between brokers but overall it's pretty stable. There are some guys who try to exploit these inefficiencies to make money through arbitrage trading strategies, though I wouldn't recommend going down that road.

Most of these inefficiencies happen during extreme market conditions so if you avoid trading the news you should be fine...