House rules differ on this.

At the Palms (and most of the rooms I play in) the rule is that an exposed card as the first card to either of the blinds is a misdeal (that is either of the first to cards of the deal).

Some rules also include any card exposed to the blind (not just the first card) as a misdeal.

Some rooms also include an exposed card to the button as a misdeal.

Most rooms (if not all) use the rule that if their are two exposed cards in the deal it is a misdeal.

If a card is exposed by the dealer and it is not a misdeal the card is used as the first burn card and the player is given a new second card at the end of the deal (the card that would have been the 1st burn card)

Remember that a boxed card -- That is a card that is face up in the deck is not treated as an exposed card. It is treated as a scrap of paper -- the card is discarded and the next card is dealty in its place.