Namaste Nishabahen,
I am adding a small explanation to points already answered with specific reference to your valid observation on analysing Celebrity Horoscope.
I think for judging the Planetary Dasha and Transits without bias -it is better to First view the Lordship of a Major Planet,i.e., it should be the lord of 3,6,12 AND badhaka sthana.
Then check where this lord is posited-if it is posited in 6th,8th and 12th-it will play a truly disturbing role. For example - For a Mesha Lagna person,Budha is lord of 3 and 6 house-if it happens to be in Taurus,Leo,Scorpio and so on counting 6,8 and 12 th from the Mithuna(3rd from lagna), Kanya(6th from lagna),Kumbha ( 11 th-Badhaka sthaana for Mesha) Meena (12 th from Lagna) - Budha dasha for adversely placed Budha will surely bring porblems.
The above is just a basic sketch and not the whole picture. We must include other factors like the current age of subject(e.g.- a 70 year old person may have some health problems happenning in 6th Lord or 6th house occupant -No Wonder !!! But a 7 year boy sufferring from lukemiea or thallesemia is surely meritting analysis and remedial action by proper worships).
As you must have known by now -Jyotisha is not a snapshot tool as many commercially engaged people make it out.
May Vyasadeva impart you strength in learning Jyotisha.
Sonat