I highly recommend liquid soap over bar form. Bar soaps can harbor bacteria, which you then spread onto whatever part of the body it contacts. Now, if you share the bar, the consequences worsen. When you use liquid soap with a pump dispenser, you are not contaminating the soap within the bottle. This adds up to a cleaner you, especially if you have breakout problems.
Contamination issues are present whenever you use a product that requires dipping (and double dipping!). Best to wash hands before putting your fingers in that jar, cake, etc. This applies to all things including moisturizer and makeup. On a relative note, it’s not advisable to pump the mascara wand in the mascara tube as this may also create contamination problems.
So, to summarize: it’s best to use a liquid soap at the sink or in the shower. Your skin will thank you with its healthy glow!