There's a lot of scammy stuff out there associated with cryptocurrencies, and Monero in particular because we pissed off the Bytecoin people and all other sorts of scamcoins.

These are considered highly trusted in the community:

poloniex.com
bittrex.com
xmr.to
shapeshift.io
monerodice.com
ottrbutt.com (Wolf's homepage. He hosts his mining software for download here. Google says its dangerous, its fine). monero.how
moneroworld.com
kraken.com
moneropools.com
monerodirect.com

These are considered scams or otherwise not to be trusted or supported (by me at least).

minergate[.]com mining pool
bter[.]com exchange
changelly[.]com/ exchange

Somewhat untrustworthy, pending full on scam categorization

safedice[.]com