Can I be ripped off with personal cheques and bank transfers?

one guy wants to send a personal cheque, however he has low feedback and has an 'african' name although his address is in kent and hasnt asked me to send it abroad.

Other guy is in belgium and wants to wire transfer funds, his account has been active for a good few years and has good feedback for a couple of high price items.

Can either of these payments be withdrawn or cancelled after they've been cleared and money has entered my account? obviously I'm not posting anything till I have money in the bank but I'm sure I read on here it can still go wrong.

Any advice?